This was the reply when I showed this to a family friend who's played piano for 20+ years, making a living from it for most of his adult life:
"You can see his little "home base" patterns that he goes to when he's kinda getting stuck. You can tell it wasn't a pre-planned piece....it would probably be even harder to play that as a prepared piece considering the pace. I'm sure he has hours and hours of various song structures he can build off of, so he probably had that basic chord progression-feel (he moves around the same base the whole time) planned out before hand.
The most impressive was his runs at the end. That was the one part that seemed to be fully on the spot (he's obviously played those run ups a million times in some form or another, but they definitely fell outside the basic structure of the rest of his piece).
Hearing a guy like that makes you wonder why you've devoted so much time and effort to something when there are people with just so much natural musical talent that there's nothing you "learn" to keep up with them."
He also said there seems to be a lot of pianists who are pure "on the spot" guys (in the sense that this guy was) compared to other instruments. The guys like that are always 'good' on the piano, but on the days where they're "on"....they can bang out production ready numbers on the fly over and over during a recording session that end up taking the sheet music writers (he had some term for the people who have to write the sheet music for the 'on the spot' tracks that end up on a record, part of a movie, play, etc., but I can't remember) days of work to get the sheet music written correctly.
