At some time in the video he's casually played a groove on the piano to back the birds for a couple of second, then stopped ("Wait, what am I doing") :)
You can also see his modular setup in the background.
I didn't know of him until today. Instantly, a new inspiration.
He has a great video where he goes through a bunch of different software that Aphex Twin used over the years. https://youtu.be/5wIOBBodoic