The only way the dragon fight could be in-game is the actual in-game fight with cinematicly moving camera IMHO. But I doubt it, I think Hines meant it's built on the engine or something.
the only real "creative editing" or whatever in the dragon fight was the camera angle changes, which while they likely wouldn't happen like that in-game doesn't mean that the fight wasn't actually FOUGHT, and the best bits of it cut out to make the fight for the trailer.
Anyway, some of the scenes, like flying around Markath's tower, definitely can't be seen from PC's eyes, so it's not that in-game.
you can recreate that in any Bethesda game by typing "tfc" into the console.
like i don't get why people are going NONE OF THAT CAN BE IN-GAME when we know virtually nothing about the small bits of the game. i've even seen people go THE WAY HE STOPS AT THE CLIFF EDGE AND THROWS HIS HAND OUT IS TOTALLY FAKE. it's like everybody started the series with Oblivion or something and cannot grasp at all the drastic differences between each and every TES title.
i mean seriously they've been working on this game for five [censored] years. even if the graphics do look identical to Oblivion like everyone is saying (fun fact: they don't), then what the hell have they been doing all this time? do you really think they just started working on the game a month or so before they announced it?
(also that rant wasn't directed at you in particular)