Here it is - The Elder Scrolls V: Skyrim gameplay trailer. Check it out:

Nick Brickon said on twitter:

Glad people got to finally see some Skyrim animation in this trailer. All that dragon stuff actually happens dynamically in-game.
To answer many questions at once: the Skyrim trailer was captured entirely on Xbox 360. Also, none of the draw-distance was faked.

And Pete Hines also said on twitter:

@OutlanderDF Yes, in-game. Only things not in-game are the shots of the wall from the previous trailer. Dragon fights are pretty epic

Also, PC gamer has posted their Skyrim trailer analysis - check it out Here