As online video consumption continues to increase, so does the online video advertising market, such as YouTube advertising ^[1]. The online advertising market has continually evolved with changes in market trends and consumer interests, as well as the development of information technology ^[2]. Despite the economic effects of the COVID-19 pandemic on the market, the global online advertising expenditure in 2020 was $378.16 billion, up from $335.6 billion in 2019, and is expected to increase to $645.8 billion by 2024. In the pre-internet era, consumers mainly obtained information on products or brands through mass media advertisements ^[3]. For this reason, advertisements were produced based on promotional or informational content.

The development of information technology has also enabled consumers to obtain information quickly from various media platforms. In this case, advertisements are more concerned with content designed to please consumers, and they go beyond just simply offering information. As online video advertisements are widespread and can be skipped due to media characteristics, users can easily avoid advertisements that are offered when watching online videos. However, advertising agents and companies of products in advertisements prefer that consumers watch their advertisements completely without skipping them. Thus, advertisements have been produced with various concepts to draw consumers’ attention. Nevertheless, it is challenging for advertising agents to create advertisements that fully attract and engage consumers.

Advertising likeability can help facilitate consumer responsiveness and generate persuasive effects. When consumers like an advertisement, the advertisement directly influences their feelings toward the product or brand presented [4,5]^[4][5]. Previous studies [4,6,7,8,9,10,11]^{[4][6][7][8][9][10][11]} have already suggested that advertising likeability is one of the important predictors of the advertised product or service sales. Few studies have focused on advertising likeability, but studies have focused on the conceptual research of advertising likeability and its effects. There is little research focused on analyzing the attributes of advertising likeability with actual data. Therefore, tresearchis study ers aimed to determine the likeability attributes of online video advertising content that increase online video advertising views and to validate them with actual user data.

2. Online Advertising Likeability

The success of advertisements and advertising creatives is dependent on consumers ^[12]. People think of advertisements as a disruption to their media viewing, and thus, they tend to avoid watching them. Compared to traditional mass media advertisements, such as TV advertisements, online video advertisements can be easily skipped by viewers. For this reason, it is critical for online video advertisements to attract viewers to watch the entire duration of the advertisement. In traditional TV advertisements, viewers more readily watch and accept the contents presented, whereas, in online video advertisements, viewers prefer not to watch advertisements in their entirety to quickly view the main media content ^[13]. In other words, viewers can choose to either watch or skip advertisements depending on their interest in them [13,14]^[13][14]. According to previous research, high-arousal stimuli increased viewers’ attraction and attention to advertisements ^[15]. In the online video context, there are several advertisements that viewers can be exposed to when viewing a great deal of online content, and the level of control of advertisements has evolved. From a business perspective, given that the revenue model of online video advertising is based on the insertion of advertisements, profits are dependent on how much advertising users are subjected to. Therefore, it is important to expose users to advertisements for more than a certain amount of time [13,16]^[13][16]. As such, advertisers strive to produce attractive advertisements with new concepts, encouraging viewers to watch their advertisements for longer or to the end. Advertising likeability may also facilitate consumer responsiveness. Likeability is related to one’s positive feelings toward, enjoyment of, or satisfaction with something. An effective advertisement is one that consumers like and intend to watch again ^[17]. The likeability positively influences the duration and intensity of viewers’ attention, brand recall and awareness, and effectiveness in generating sales [8,18]^[8][18]. Therefore, this study defines online advertising likeability as viewers’ liking of and satisfaction with online video advertisements and desire to watch them again ^[17]. If viewers have a greater likeability for a particular online video advertisement, they will have the intention to watch it to the end or again ^[4]. In addition, advertising likeability directly influences viewers’ feelings toward advertised products or services ^[5]. The roles of advertising likeability and likeability in the advertising process have been analyzed in some studies [11,19,20,21]^{[11][19][20][21]}. Regarding components of advertising likeability, in traditional advertisements, likeability was presented as a complex concept involving various factors and was identified with five dimensions: ingenuity, meaningfulness, energy, warmth, and rubs the wrong way ^[4]. For the attributes of advertising likeability, Fam ^[22] identified seven dimensions based on five countries, which were entertaining, warmth, relevant to me, soft sell, strong/distinctive/sexy, status appeal, and trendy/modernity/stylish. For online video advertisements, entertainment, informativeness, and credibility positively influenced the attributes of advertising ^[23]. Compared to traditional mass media advertising, online video advertising features high user control over watching advertisements. Therefore, it is necessary to generate a more strategic advertising creative. Since online video advertisements are inserted into online videos on social media, it is possible to collect viewers’ revisewsarch about advertisements in such media. Therefore, this study aimed to identify key attributes of advertising likeability and to validate them based on advertising content by analyzing viewers’ reviewssearch on popular online video advertisements.

3. Studies on Online Video Advertisement

Online video advertisements have drawn massive attention and gained more views through online video platforms, such as YouTube. Online video advertisements are advertisements inserted in online video content. Viewers tend to skip these advertisements to watch their main media content more quickly. Notably, watching online video advertisements is highly controlled by viewers according to advertising likeability. Therefore, it is important to reflect advertising likeability that compels viewers to watch advertisements without skipping them. However, most research on advertising likeability focused on the advertising content of traditional mass media. Regarding the online advertising context, previous studies have mainly aimed to determine the characteristics of online advertising and their effects. Table 1 summarizes previous studies on online advertisement. Tellis et al. ^[24] examined the characteristics of advertisements that induce online advertising virality. The study found that positive emotions, such as amusement, excitement, inspiration, and warmth, positively influenced sharing. However, information-focused content, except for risky content, negatively affected sharing. In addition, a variety of drama elements, such as surprise, plot, and characters, including babies, animals, and celebrities, aroused emotions. Wai Lai and Liu ^[25] analyzed how content likeability, content credibility, and social media engagement influenced user acceptance of product placement in mobile social networks. The study found that content likeability, content credibility, and social media engagement directly affected user acceptance of product placement in mobile social networks. Social media engagement influenced content credibility, and content likeability was an antecedent of social media engagement and content credibility. Shehu et al. ^[26] examined how likeability dynamics influenced consumers’ intention to share online video advertisements. The study demonstrated that high likeability from the beginning to the end of an online video advertisement is important. Goodrich et al. ^[27] examined how advertisement characteristics, such as length, humor, and informativeness, influenced perceived ad intrusiveness and marketing outcomes. The study found that intrusive advertisements negatively affected attitudes toward advertised brands and host websites and intentions. On the other hand, it was determined that informative and humorous video advertisements and longer advertisements dampened viewers’ attitudes and intentions to a lesser extent. Dehghani et al. ^[28] identified the dimensions of YouTube advertisements that influenced advertising value and brand awareness and analyzed consumers’ purchase intentions. The study found that entertainment, informativeness, and customization were the strongest positive drivers of purchase intention, and irritation negatively influenced purchase intention. To predict the instantaneous likeability of advertisements, Saha et al. ^[29] proposed a prediction algorithm based on deep learning and compared it with other methods. ThRese authoarchers classified advertisement clips into five categories (i.e., entertaining, creative, emotional, humorous, and miscellaneous) based on the overall impression of raters. Puwandi et al. ^[30] examined factors that influenced consumer response to video advertisements. The study found that consumer behavior toward online video advertisements positively influenced consumer response, and intention to watch the advertising, flow, and corporate reputation positively affected consumer behavior. In addition, informativeness, entertainment, and credibility positively influenced attitudes toward the advertisement, whereas irritation negatively affected attitudes toward the advertisement. Most studies on online advertisements have focused on the characteristics and effects of online advertising. Although there have been some studies focused on the likeability of online advertisements, most studies have adopted concepts used in previous studies. It has also been rare to analyze the likeability attributes of advertisements watched by viewers. In addition, most previous studies have used perception data through survey methods. Saha et al. ^[29] proposed a prediction algorithm based on deep learning methods to predict the instantaneous likeability of an advertisement. However, they did not classify the advertisement into likeability factors from the perspective of viewers and validate them. Rather, they focused on developing a prediction model for the likeability of advertisement and validated its quality. That is, few research studies have derived the factors of advertising likeability of online video advertisements from the perspective of actual users (viewers) and validated them. Therefore, tresearchis study ers aimed to derive and validate the likeability attributes according to viewers from the content perspective of online video advertisements by utilizing actual data.

Study	Method	Objective	Results
[30]	Survey (descriptive survey)	To examine factors that affect consumer response to online video advertisement	Showed that consumer behavior toward online video advertisement positively affects consumer response
[29]	Deep learning	To predict instantaneous likeability of advertisements	Proposed algorithm to predict instantaneous likeability of advertisements and compared the algorithm with other methods
[25]	Survey	To investigate the effects of content likeability, content credibility, and social media engagement on users’ acceptance of product placement in mobile social networks	Showed that content likeability is an antecedent of social media engagement and content credibility; social media engagement has an influence on content credibility; and content likeability, content credibility, and social media engagement both directly affect user acceptance of product placement in mobile social networks
[24]	Mixed-effects regression	To understand ad-related characteristics that drive virality (sharing) of online ads	Found that positive emotions of amusement, excitement, inspiration, and warmth positively affect sharing
[28]	Survey	To identify dimensions of YouTube advertising that may affect advertising value, as well as brand awareness and, accordingly, purchase intentions of consumers	Showed that entertainment, informativeness, and customization are the strongest positive drivers, while irritation is negatively related to YouTube advertising
[26]	Survey	To examine the effects of likeability dynamics on consumers’ intentions to share online video advertisements	Found that high likeability at the beginning and the end of a video advertisement is important
[27]	Experiment	To examine the effects of advertisement characteristics (i.e., length, humor, and informativeness) on perceived ad intrusiveness and on marketing outcomes	Showed that intrusive advertisements negatively affected attitudes and intentions toward both the advertised brand and the host website