^^^^that's always a concern but I don't think that's the problem, or if it is it's not the
only problem
OP, I went to your site and clicked on two of your videos randomly. The first had a one line description that didn't appear in google when I did a quote search, while the second had a full paragraph of text. I did a quote search in Google on that and found
this. Two random pages on your site, the first thin content (one line of text on the whole page) and the second a paragraph that appears on multiple sites all over the web. Ish like this will kill your search rankings.
It could be a link (Penguin) issue as well though, do you recall when the site's rankings first fell? Timeline is a great was to narrow down which issue caused the fall.
Even if your backlink profile is sound though, you need to work on unique, meaningful content. I know the guys are there to wank and watch, not read, but search bots read text. Without that I don't imagine you'll have much luck long term, even if you start over with a new domain.
It could be a scraping issue as well like Barry suggested, but even without that I really doubt that your site will recover unless you solve the on-site issues. Start first by isolating when the site fell. If it corresponds with a Panda or Penguin refresh you'll know exactly what issue(s) you have to tackle. If it's Penguin then Barry is right, start over fresh on a new domain (with no 301 redirect). If it's Panda transferring the content to a new domain will only result in the same thing all over again.
I wish you good luck, and happy new year