If you haven't seen the movie, I highly recommend that you watch it at least once.
The CMs usually spiel that if you do not wish to view the movie, you may bypass it by walking straight across the theater throught the open doors.
The CMs are not offended by people who do not stay for the movie. If you don't want too see it, why are you so concerned about hurting their feelings by leaving?
The doors stay open for quite a while. The CM in the theater controls when the movie starts, so he or she will not start it until everyone coming in or going out is situated. If the doors close while you are en-route to them, simply push them open. They do not lock, and as long as the movie hasn't started, you won't be thought of as rude (if the movie has already started, you won't be able to get
in to the theater, so this is not likely to happen unless you actually
are a rude person, in which case, what are you worried about?

Seriously, though, there's no need to run or even to "walk VERY VERY fast," there's no trick to it, you're not getting away with anything, because it really is no big deal.
(it is, however a big deal if you feel the need to press the "Wheelchair" button that holds one set of automatic doors open for a couple of minutes. If you're not in a wheelchair, don't touch it. That too will make you look rude... again, if you are rude, nevermind.)