then the official stands over the ball on the line of scrimmage- not interfere with the QB....
One cannot tell from the clip about the timing of the substitution, but the center is over the ball. Maybe Free Shoes U had run in a late sub. What normally happens is that an official places the ball down and then moves into his position.
If all the officials are in their normal position, then the closest one to the ball is in the backfield. Getting over the ball in that situation is pretty tough. Holding up the snap, in compliance with the rule, is the operative principle here.