Selected answers from the Dumb SEO Questions Facebook & G+ community.
Youness Bermime: Find someone who has written content relevant to your youtube video and send it to them. Usually, if the video is good quality and a match for their content, they`ll happily add a link to it or even embed it (which works as a backlink for youtube as well, I assume). Don`t forget to mention that adding a video may increase Time On Page which may indirectly increase their rankings.