"This is an audio recording of a piano roll. That is to say, Debussy played on a specialised piano with made cuts in a roll of paper as he played, this was played back more recently by a piano mechanism which translated the holes into which notes to play, and this second performance was recorded in audio, which is what is played in this video."
"I saw this device at the Music House Museum in Traverse City, MI where we were treated to the last section of Rhapsody in Blue that was actually played by Gershwin himself. The speed at which the music was played needs to be set by the person setting up the roll, but otherwise dynamics, touch and pedal are all preserved. These types of pianos have been known to receive applause after performances because of high level and quality performance."