TubeMogul reports that the vast majority of online video is 'discovered' either by visits to a video website (no real surprise there), or via blogs (which is surprising). Here's a graphic showing the breakdown from NewTeeVee:
Audience building is one of the holy trinity of internet TV (content and platform are the other two), and perhaps the most difficult of these disciplines to get right, so there are some real pointers in this report.
I'm not sure what methodology was used, but the figures are very surprising - the majority of videos I watch outside mainstream services are sent to me by email. How do you find video ?