  Many online video websites provide the shortcut links to facilitate the video
sharing to other websites especially to the online social networks (OSNs). Such
video sharing behavior greatly changes the interplays between the two types of
websites. For example, users in OSNs may watch and re-share videos shared by
their friends from online video websites, and this can also boost the
popularity of videos in online video websites and attract more people to watch
and share them. Characterizing these interplays can provide great insights for
understanding the relationships among online video websites, OSNs, ISPs and so
on. In this paper we conduct empirical experiments to study the interplays
between video sharing websites and OSNs using three totally different data
sources: online video websites, OSNs, and campus network traffic. We find that,
a) there are many factors that can affect the external sharing probability of
videos in online video websites. b) The popularity of a video itself in online
video websites can greatly impact on its popularity in OSNs. Videos in Renren,
Qzone (the top two most popular Chinese OSNs) usually attract more viewers than
in Sina and Tencent Weibo (the top two most popular Chinese microblogs), which
indicates the different natures of the two kinds of OSNs. c) The analysis based
on real traffic data illustrates that 10\% of video flows are related to OSNs,
and they account for 25\% of traffic generated by all videos.
