[Pazzaz]

I think you're exaggerating a little when you say "site:youtube.com" doesn't work. If I search 'site:youtube.com apple watch' I get 143 000 000 results, and if I search something more specific like 'site:youtube.com "Featuring Dr James Grime"' I'll find exactly what I'm looking for. But you're correct that it doesn't seem to search video comments, only titles and descriptions.

[derefr]

The problem I ran into is that, like I said, YouTube doesn't seem to get indexed by hypertext inward-edges from other sites like a regular website does — and so you can't search by how you recall a video being described in pages that link to it; instead, you have to remember how the video describes itself. Which it may not always do well.