I know Vimeo does.

I just discovered Funny or Die has a mobile version. The videos play beautifully in high res:
http://m.funnyordie.com/videos/4a87d48fdd/undercover-karaoke-with-jewel

I know there are some NBC clips and a few shows available, but it seems less than there used to be.

What other video sites have you found that play on webOS?