I'm not sure I understand your question... You mean someone who has already seen the end of the movie will learn (or be reminded of) nothing new if they saw it again? No, I'm not assuming that (there aren't that many people with perfect eidetic memory around), but I can't see the relevance. My point is not that the value of watching a film/reading a book when I already know its ending is zero; it is that the value of watching a film/reading a book when I already know its ending is strictly less than if I didn't knew it. (How much less depends on the type of film/book.)