YouTube video-game streaming is a popular entertainment among young consumers. As a result, product-placement activities in YouTube video-game streaming have become one of the vital advertising tools, yet there are some concerns about how it might lend undesirable effects on young audiences. Therefore, to prepare advertising practitioners to cope with any issue that might occur, this study aims to 1) explore young consumers’ exposure, attitude, and behavioral responses to product placement in YouTube video-game streaming, and 2) examine the influence of consumers’ exposures and attitudes toward product placement through YouTube video-game streaming on behavioral responses among Generation-Y and Generation-Z groups. The results from a survey of 463 Thai samples show that most of the respondents’ exposures to the product placement within video-game streaming are interwoven into the video narratives and that the respondents have positive attitudes toward eco-friendly products while agreeing that there should be regulations for online product-placement practices. Most behavioral responses of the respondents are their preferences to follow the game-streamers’ channels. The result of the t-test analysis shows that Generation-Z respondents exhibit more behavioral responses than Generation-Y ones. Furthermore, multiple-regression analysis reveals that the most influential factor towards consumer behavioral responses is the affective or “Feel” component, such as positive attitudes toward eco-friendly products for online product-placement practices, product preference, reliability, and positive attitudes toward game-streamers’ product-placement activities.