This is another Hari Kari thread, there doesn't seem to be any on this page and I can't bump any so this is a new one.

After seeing that new trailer just now and seeing the Hari Kari move. It seems that the winner of the match performs it on him/herself rather than the loser as we have always thought?!

Looking at that part of the trailer you can see that Kenshi had been defeated because he is spinning like they do after a match but before a fatality.

So this would mean that it won't be a matter of who has the quickest hands/fingers to perform the fatality first. It's always the winner that can perform the finishing move.