When I first saw this - I couldn't believe how cheap a shot it was.
But I was wrong.
Turns out- it was totally legal because the ref never waived the guy off! The dude just turned and walked away- pretty dazed from the beating he just got- which meant it was legal hit! Never turn your back on your opponent in the middle of a fight!
Turns out - the fans didn't realize that before they jumped into the ring and started a melee!