In all fairness if they made trailers/campaign videos that showed only what you could physically do in game then 99% of them would not be the same. Remember they cant have that level of realism / awesomeness in game through both technical and balancing issues.
I mean cmon have ever tried jumping from space onto a planet in halo? doesnt ever work out well despite the chief showing it can be done XD
but jokes aside ask yourself this, was the trailer awesome???
if so then it did its job, which was to psyche you up for what was and is an amazing game despite its flaws