Hey Kevin,
I don't agree that a good teacher has to be a first rate virtuoso who can play everything attempting to teach.
About genetics, I don't know if you have to be born with it, but playing the piano from an early age can certainly help.
If you can play Earl Koenig at 140, you're in pretty good shape, or is it the Appassionata that you can do at 140?. Appassionata is easier, as the repeated notes alternate between the hands, so there's time to rest.
The first thing I'd recommend is to practice the "butterfly technique", which is using your hand from the wrist only, moving the hand up and down like a butterfly wing, not using and/or moving any other part of the entire arm.
This will serve you also for chromatic octaves, scales in octaves and chords, etc.
The next thing is very similar to what the woman in the video suggested (in spite of her being of the Taubman-institute, as the url suggested, when she demonstrated, her hand looked very tense):
Move your wrist slightly up while moving the whole arm slightly further in on the keys (towards the back board) and move your wrist slightly down (back to the starting position) while moving the whole arm slightly back/outwards on the keys.
But there's one difference between what she suggested and what I suggest.
She moved in and up playing 5 1/8 notes and moved back and down to her original starting position on the 6th 1/8.
What I suggest for this rhythm is moving up/in and down/out every 3 1/8 notes.
BTW, I'd recommend practicing to start both ways 'in/up - out/down' and 'out/down - in/up'.
Also, don't limit your wrist to only moving up and down from a leveled starting point, but also down first and than up, meaning the wrist can move up and down beyond the starting level point and not only above it.
Whatever tempo you can do at whatever piece, this practice will gain you some extra notches on the metronome, and will keep you hands healthy.
Best wishes and good luck,
Rami
https://www.youtube.com/user/barnivhttps://ramisrhapsody.tripod.com/