You probably want to see
this. Apart from the first 20 seconds or so (with the giant mech thingy) it's all ingame footage. It looks, frankly, brilliant.
The link above is a 300k video stream unless you have a GameSpot account. A much higher res 300MB quicktime file is available
here, although personally I think quicktime is all but useless as the free version won't even go full screen. You could probably play it in VLC or similar though.