Google Video is also a great collection of videos. You have to download them but they are of good quality.
I was looking for some racing videos, typed in rc cars and got - 370 clips.
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You don't have to download them to your computer to watch them... I actually have a few of my videos posted there but I get like no views so it's not the greatest. The also mess with the sound and the quality is horrible.
YouTube is still on first place at my side, but it's good to have a list of main video sites.
Yahoo videos has at least two times as big video collection as YouTube - I mean beside their own videos you get direct links to videos on other video sites - including YouTube.