User-generated health videos are prevalent on video-sharing sites. Recently, “bro-science” has emerged as a sub-genre in which users test products on themselves, produce evidence and seek to persuade others of their efficacy. But what are the motivations of the producers of these videos? Using the issue of baldness, we explore the motivations of posters. 72 “bro-science” videos were taken from YouTube and analysed to see the motivations identified by posters. These included a sense of external compulsion, the desire to communicate product benefits, wanting to share careful research, and wanting to share experiences. We also discuss how these motives function rhetorically. The “bro-science” genre thus functions to incorporate the viewer into the poster’s experience so that the viewers become part of a community of people who not only share problems, but solutions. This paper points to the distinctiveness and influence of “bro-science” videos in the context of user-generated health videos.