In this case, it could also be translated as the "theme" of the film, I think!
Can I say O que e o tema do filme? what is the difference between qual and o que??
Man, I was so confused by this. I really wish DuoLingo wouldn't use words in a sentence without giving the proper definition for that instance.
Maybe in Spanish, but not in Portuguese, where "película" means only "thin layer", but not "movie/cinema".