Another bit of the “Friends” piece (and others) comes from Rachmaninov. This info should be incorporated with that here.
The first video is of his famous prelude (which he called “it” as he got fed up with playing so often). This music represents corpses(ghouls) rising from the grave at night, walking around a bit doing what they are supposed to do, and then going back to their graves. This is the composer playing his piece into a clever piano roll that recorded dynamics as well as notes (a bit like mechanical MIDI) in 1919!
The second is there because it’s there. This is the composer again, recorded in 1929!
It’s so marvellous that this stuff of one of my heroes is becoming widely available.