I was just wondering. I see that youtube videos are having an pagerank of 4 while they only got like 10.000 views and 20 comments. What if you make and video and backlink your website from the subscription? Then you have to outrank everyone within your keywords? Are there people that has done this kind of 'seo'? I'm seriously thinking to try it out, because i saw and video of an soundtrack of a game. With an static picture and it has an pagerank of 4 while it was 4 months old!!!
What is the PR of the subscription page? If it is PR1 then the videos PR4 won't matter much since you aren't getting the link on the video page. You can put links below the video on that page.
YouTube links from the video are nofollow, so they're not going to pass on any PR to your site. But that's not a bad idea to link your YouTube channel to your main site, because this link will diversify the backlink profile and won't hurt search engine rankings. You may also insert the link to your main site in the 'Website' field on your YouTube channel (this one even used to be dofollow).