people are interested in seeing a movie exactly once
Uhh...where did you get this information from? Most people I know watch the same movies more than once. All of my friends have a few favorite films that they would easily watch over and over (Office Space, Star Wars, Rocky Horror Picture Show etc.)
Music relies on people wanting to hear it multiple times and they are probably more interested in the music well after it exists. And complete knowledge of the contents of the music increases, rather than decreases, their desire to hear it.
Have you heard of film studies? There are numerous journals (Cineaste, Film Comment, Film Quarterly etc.) and books etc. that discuss films in depth and I can definitely argue that "complete knowledge of the contents of a film increases, rather than decreases, the desire to see the film again and again..."