Shame, I just voted for Pop is Dead, but then I thought, "Hey, you used to watch Go To Sleep before you even liked Radiohead and now... It's too late.
Idiotheque is great because you can see Colin playing the keyboard at the beginning.

And... I also like Knives Out, it's so bizarre and the first Radiohead video I knew... Before I knew who it was. I was to find out five years later.
Well, I had that with Don't Look Back In Anger... I knew the video, but not the song.

Street Spirit is technically really good.
But I stick to the ridiculous hilarity of Pop is Dead.