Google's purchase of YouTube was, in my humble opinion, stupid. In that google fails to recognize what YouTube's biggest attraction is. (At least to me)
You Tube frequently hosts entire episodes of television shows and large quantities of copyrighted material.
Google frequently deletes this material from google video.
So when Google owns YouTube the copyrighted material will actually have to be removed. And I think this is going to drive traffic levels down significantly as viewers find other sites that host the last episode of South Park.
Now, obviously I could be overestimating the amount of copyrighted stuff on YouTube. There are certainly a lot of home movies and such. It would be interesting to see how much traffic was generated by copyrighted items vs. non copyrighted items. I hope Google did that analysis before they made their purchase.