UPDATE: Commenter Charles Reichley breaks it down:
I’m surprised it worked. At least one person on the defensive line should have been watching the ball. As soon as the center moves the ball at all, that person is supposed to signal and rush. Because you can’t be certain the quarterback is going to say anything, or move, when the ball is snapped, and you can’t be certain that if the quarterback moves, he’s snapped the ball.
But nobody on the line moves an inch. Which means they were all watching the player in front of them, rather than the ball.
I guess we could blame the other players, but they may not know exactly how the quarterback came to be holding the ball, because they cannot see the snap.
That’s why the line has that job. On the other hand, once the ball is set, if you see ANY player with the ball off the ground, it’s time to tackle, unless you hear a whistle.