In-game doesn't mean much, though. It only means that it was rendered using the game engine, it could be all scripted though. And some parts obviously were scripted, like the stop at the cliff or the death of the dragon. I highly doubt that stuff will be as dynamic in the actual game.
When they have worked on dragons for 2 years, especially, it seems, concerning how they move and react in every single situation, I'd say it's very very likely it will be the same as it was in-game as in the trailer.
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Anyway, I think this should close the thread. Read carefully: http://bethblog.com/index.php/2011/02/24/first-in-game-skyrim-trailer-released/
"First
In-game Skyrim Trailer Released!"
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Also, OP. You said: "
In the gameplay trailer, when he is running through the woods.."
And then ask: "
Do you think those were in-game?"
Kinda breaks logic here.