The thing about tatum is that he worked out a technique for himself, which is why it’s so hard to play. Eg he has chords with 10ths in them in a striding bass at impossible speeds - unplayable for 99% of pianists.
His hands are HUGE
like his tech
supposedly he learned by feeling the keys on a player piano that was doing 4 - hand music!
“Born to play the piano”, as they say. His fingers barely move on that video, what an incredible conservation of motion.