If you watch it carefully you see its relatively simple to explain (hard to actually do):
He leans a bit to the right whilst still in the air, and looks that way too as if he is going to offload in the same direction after a step or two post landing. Instead he actually does a little goose step with his left (I.e the one he was feigning to be going to push off on) then pushes off into a straight rugby league style side step on his right.) It's a simple enough move to copy; even fat early middle aged me can do it in the backyard. BUT why everyone is rightly creaming themselves at what it shows about his potential:
1) In that situation you have to conceptualise what you are going to do all in about 1/4 of a second and start doing it
2) Not worrying that you will fail under the direct pressure of your opponents and the indirect game situation pressure
3) Actually do it fast enough that AFL athletes won't catch and flatten you.
So whatever else and injury notwithstanding we already know he's going to be an above average player as in game one ball in hand the world is not only not a blur for him, it's obviously crystal clear and in bullet time slow mo.
It’s not so much the sidestep. Anyone can sidestep. It’s more that he sold it so well that both defenders went the complete other direction.