It would be cool if, when playing a soundtrack you would see a link to play the movie if it’s in your library. In addition, it would be nice to be able to see a link to play the soundtrack from the movie screen.
Further, you could link the soundtrack to the movie so when hovering over or selecting a movie, if you have the soundtrack in your music library, it would start playing it. In that case, if you had two versions, say, an MP3 and lossless FLAC, when hovering over or selecting a movie, it should stream the lowest bit-rate version to save of bandwidth.