I watch game reviews, mainly zero punctuation and occasionally an IGN video review.
I also really like day[9]s videos. He recently did some diablo 3 beta vids and an amnesia playthrough for halloween which was funny.

Those are the only videos I watch semi regularly I think.
Oh also the occasional sc tournament when they come around.

Oh how could I forget, any decent TED videos that I come across I usually watch because, well, they're awesome.