In my experience, I've found that you should never base your ideas of a game off any video or screenshots released before it. Wait for screenshots and videos after its release then decide on it.
Even though it may not be prerendered, they will always take the videos in the best-looking spots with the best weapons and characters in choreographed sequences that don't necessarily give you any idea of the gameplay or even how the game will look. There are a few exceptions, and for comparison look at the battlefield 1942 videos and the battlefield 2 videos.
I just "ooo" and "aah" at the videos, then ignore them as I would a teaser trailer for a movie.