The Star Citizen "Imagine" trailer begins with a note stating that all footage was "captured in engine," which I think is an interesting distinction from being captured "in-game." Not that it really matters in this particular instance, because this video is really more about you than it is about the game.
Will you be an elite jet-jockey? A sharply-dressed trader, looking for the next big score? Perhaps an explorer, picking through ruins with a scanner in one hand and a gun in the other? Or maybe you'll find yourself standing on a flight deck somewhere, sucking back your third coffee as you wonder how you're going to cover the cost of fuel, your mortgage, and that wildly overpriced private school your wife insisted that your daughter attend.
It's all very aspirational (well, except maybe for that last one), and whether Star Citizen will be able to live up to its promises is a question that's a long way from being answered. The recent release of Arena Commander 1.0 is a big step in that direction, though, and good game or not, the boundless reaches of space sure do make for a pretty trailer.