of course the mass media/movie production can change society. But i wouldn't use word "help". "help" is something positive, while mass production can affect society very negatively. Movie can definitely form a certain images, pattern behavior, stereotypes, etc.
All Film companies reduce the number of smoking scenes in their films, some of them have banned these scenes completely.
Movie creates stereotypes that are followed by people. Girls want to look, to be dressed and to behave as their favorite actress. Guys want to act like their hero acts. This is normal process.
Brit, one separate movie might not help one individual become better (but also MIGHT help), but creating a whole image of certain behavior and stereotypes in the society definitely can make this society better (or worse)