The weapon firing is all fake. When the first gun fires a grenade onto the bridge there is no actual projectile.. just an instant explosion...
Also when the player is shooting under the bridge it is obvious the gun is not producing any effects... just timed sparks and stuff when shooting enemies on top of the bridge.
If this is actual engine footage running on PS3 that we can expect the title to have, then fuck me. But otherwise it looks like pre rendered stuff with first person weapons to fool the public.