Also, above is a known, if rarely used, throw-in technique. I guess it helps increase the bend/snap of the release? There's probably some smart engineer or physicist who can better explain it (or explain why people think it helps, if it actually doesn't). But the long throw-in is a weapon for teams that have it, and the summersault throw-in is intended to be a long throw-in.
But if you really want to get nerdy, the sequence of the throw-in above shows that it should not be allowed (or, to be more technical, is a foul throw). In that player's motion, the ball never comes over her head, which is a requirement. Instead, it is always in front of her head/forehead.
But no one cares. It looks cools, and few players do it, so it is always a little novel.
