From The Good, The Bad and The Ugly (1966). The scene where Tuco and Blondie are hiding amongst the POW in the Union camp. Lee Van Cleef is kicking the shit out of Tuco and a band of prisoners play this outside to drown the sound of his screams. Simply put, its one of the most achingly beautiful pieces of music I have ever heard.
Allegedly, Mickey Knox, the man responsible for making sure the English translation synched with the Italian actors mouths struggled for days to find the words to fit when the soldier tells them to play louder. He needed two words to fit. He came up with "more feeling" as the young prisoner starts crying.