I thought this was a rule?

I thought that the linemen had to be down and relatively still when the ball is snapped, not waving to the sidelines and all of them making signaling motions. Still not sure how that wasn't a penalty, certainly is (or atleast once was) in the Florida high school system. The announcers were calling it a 'good play', and I was there thinking, "No, that's actually a pretty straightforward penalty..." But I guess I'm wrong.