I've done it 33 years and have never seen a snapper get the snap to go forward over his head past the NZ. But if you say so...
I would have to say this is an illegal snap. A legal snap is supposed to be a backward pass, but this one went forward so how could it be a legal snap? Ruling it as an illegal snap would have the benefit of getting it killed for a semi-routine 5 yard penalty and not becoming a cheap turnover which might be way too exciting. (In fact, if the play didn't start with a legal snap, then the ball would never be live in the first place.) One thing it can't be is a fumble. A backward pass could only be muffed, not fumbled.