This sleight of hand pitch doesn’t seem like it should be legal despite the umpire allowing it. Although to be fair I don’t actually know the rules of pitching. All I know is you can’t balk (fake a pitch) and once you start the windup you have to deliver the pitch in one continuous motion. I’m assuming the umpire knows more than I do, I just feel like I’d echo the sentiments of the voice on the video going, “Ah, what the fuck.”

Source: Geekologie – Questionably legal sleight of hand baseball pitch