I DID NOT TAKE THIS, I DID NOT ATTEND E3. THIS WAS UPLOADED BY SOMEONE ELSE WHO DID PLAY IT
This is a demo from E3 from the new Metal Gear Solid game for the Nintendo 3DS. Here, it is just a non-playable walkthrough, but it is rendered using the 3DS' real hardware real time 3D. Has some amazing graphics, and to prove it's not prerendered or recorded, you can adjust the camera angle with the analog slider. No sound when i found it. This will eventually be a full game, now it's a bit of a tech demo to show the 3DS off.