Abstract The sharing and re-sharing of videos on social sites, blogs e-mail, and other
means has given rise to the phenomenon of viral videos—videos that become popular
through internet sharing. In this paper we seek to better understand viral videos on
YouTube by analyzing sharing and its relationship to video popularity using millions
of YouTube videos. The socialness of a video is quantified by classifying the referrer
sources for video views as social (e.g. an emailed link, Facebook referral) or nonsocial
(e.g. a link from related videos). We find that viewership patterns of highly
social videos are very different from less social videos. For example, the highly social
videos rise to, and fall from, their peak popularity more quickly than less social
videos. We also find that not all highly social videos become popular, and not all
popular videos are highly social. By using our insights on viral videos we are able
develop a method for ranking blogs and websites on their ability to spread viral
videos.