Do you believe everything you see? This is an computer generated movie clip and no ingame shootage. The stock FSX is a piece of crap without any 3rd party addons.
It's not an FSX trailer but an MS Flight trailer, the new sim announced by Microsoft. And I have never seen a FS or FSX trailer based on something else that the game itself. Notice that the symbolic omission of the word "simulator" gives us an idea of what to expect