If someone I just killed would approach me homing-missile-style and then dance right in front of me while I got hit by arrows in the middle of a fight, I might probably strike them down, double kill or not. The situation was heavily provoked. Also, in one of the last few frames, the hand-wave from the walking is very different - as if a punch is happening.
The no-double-kill rule was instated to ensure a clean game. Where people are not harassed. Where people can recover, work themselves up the weapon ladder and so forth. It was not instated to prevent clearly provoked attacks.
Nothing to see here (except a player who somehow wants to get someone else banned). Bounceh, if you made that video to prove Jov's overall behavior that you might have experienced earlier, then it's a failed attempt. Nothing is proven either way.
Side note: SgtSpike will probably have Socrates implement something that people can not attack other people if they killed them before - until they get attacked by the killed guy again.