I'm sorry, since when did playing video games become "mentally passive"? (I say that somewhat half-jokingly.)
While reading I'm sure is much more healthy than playing video games, I don't think you can put video games -- for the most part -- in the same "mental" classification as watching a movie. Most video games require thinking and coordination.
Movies, on the other hand, barely require thought, zero coordination, and free your hands up to stuffing your face with processed goodies.