I just witnessed the video, running at ~50fps (you need a blazing fast computer for this movie to run good, seriously. 2.8ghz here and it would sometimes be a tiny bit choppy).
But from what I saw... whoa... the screenshots do NOT give a good representation of next-gen AT ALL. The resolution and quality of the game/picture really gives me a better-than-at-home arcadey feel. The fine details in everything look amazing. Of course some things need to be ironed out (I'm not fan of the water, or hair going through body parts), but I'm sure that will be improved in time. Overall, I'm mighty impressed. I can't wait for IGN to post more of these.
Masterbit video of Killzone? Please?
Edit: Oh and why the huge filesize? Run this on a potent computer, and you'll understand why. 60fps footage at this high resolution is absolutely insane.