its not pre-rendered its just a real-time scripted cut scene. the movie you saw uses the game engine but there are less factors (AI, physics, etc.) to draw from the system's resources and gives the developer the ability to make the graphics look better. its been done for years and will always happen to expand the cinematic experience. just look at how much better the movies in halo 2 look compared to the game, any of the previous MGS, shenmue, RE: Code Veronica, and many other games. that is because like a film director aiming for the best shot, in a scripted cut-scene a developer has the chance to use the best lighting, textures, angles, redirect more polys where needed, and control every aspect of what you are seeing.
its safe to say the actual game wont look that astounding, though it will still look great. on the 360 we havent actually scene many cut-scenes and most of the vids are just gameplay where physics, AI, and other factors draw from the graphics.
i think it looks great but nothing that the 360 can do as well. it is unfair to compare this to any other game on any other system as its been built on the ps3 from the ground up on dev kits that are 80% of the systems total power, where on the 360 all the games you have seen so far have been developed on altered G5 Macs that would consist of around 25% of the 360's power. even now most of the vids you see until X05 are still only on the beta kits (60% power) and things will all be clear on how powerful the 360 is when games are being developed from the ground up on its actual hardware. most of the impressive points of the vid is the 60fps frame rate and the texture work. in this gen it will matter more on texture work and effect to show the developers art style and provide an impressive scene on the TV. polys arent as important as in previous generations.
