Movie

Why do some movies stay with you, so that you can remember almost every scene for years afterwards, and others you forget the plot of immediately, even if you enjoy them?

I rewatched "The Departed" on TV, which I definitely saw before, but didn't remember a damn thing about. Scenes looked familiar, but it was still like seeing it for the first time. Anyway I enjoyed it again, and will probably remember it better this time, especially considering I had dreams about it that night...