IMHO, there's someone clearly controlling Snake in that sequence. The Gekkou is merely going through various attacks + Snake is just dodging it with a new set of moves.
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At my first glance of the vid, it looks like they tied Snake's new spin/roll ability into the tilt functionality of the PS3 controller - and it looks brilliantly done.
Being able to go prone, spin/roll face up, go into first person + shoot while on your back is awesome stuff. Add in the ability to toss a grenade over your shoulder while on your back and that's just beyond greatness.
Take a look at the second part of the second vid-
Snake crawls in the middle of a firefight between those Foxhound + rebel looking guys. He then roll around to a face up position, tosses a grenade towards the Foxhound guys. Then he rolls a couple times again to avoid fire, pulls out his handgun + shoots at the other two insurgents.
That's just flat out awesome right there. And that's not even taking account the fact that there's a rebel faction and a foxhound like faction fighting each other on the battlefield.
The spin/roll combined with the Octocam = a nearly unlimited amount of places to hide, despite one of the themes being no place to hide.
I have a feeling the tilt function of the PS3 controller is also tied into the traditional Metal Gear wall lean, as it appears you can now turn + face the wall while leaning against it.