Forgive me, but I as well as a lot of people are having trouble beleving this? Would you care to show any proof if there is? I mean, it's obvious the cameras were done, and if you will forgive me for saying so, it just seems too perfect a trailer to be in game. And if it is NOT in game, just say so. Really, with all the other work in game, noone will hate you except for the original lie.
Just because the camera angles were more cinematic and the dragon-fight very... coordinated... doesn't at all mean it's not real-time rendering from in-game.
With the console in Oblivion, tfc would toggle a free-flying camera not bound to the player at all. And cinematic sequences can be done with that, despite the fact that it's still in-game.