You will see a visual display of the music as it is played (by real musicians). I believe that Smalin, the author/artist/creator, has written a program that takes a midi file as input and produces the visual display as output. This is then synced to a real performance, hence the good sound. On the author’s youtube site there are many more pieces like this, some with a more straightforward display. This one is especially artful.
zipTimer: an app for pacing your music practice – or any practice!