I think it is a little harder to spam YouTube (with content) than the web. On the web, you can just parse feeds/spin text. On Youtube, you have to upload things. According to the presentation, they built out studios and are recording videos at a fast pace (and they do have thousands of videos on their channel, all with a signature white negative space backdrop). It is totally possible to make bad videos, not denying that. But it's a bit harder to trick systems into thinking there's something there that's not/misdirect.
Not saying there aren't other places in the system to abuse stuff (On YouTube you can friend spam, Fave-spam, etc), but it's hard to do with content.
Were you thinking content spam?