You are obviously talking about 2 head Fatality, not 3 - that one is in MK2, I myself mixed it up thinking 3 heads were in MK1 but after searching on the net, I'm almost 100% sure 3 heads in not possible in regular versions of the arcade MK. I can do 2 head Fatality on Kano and ninjas without breaking a sweat, I did it few times today on MAME, trying like an idiot to do 3 heads but no way in hell, and I'm fast.
Talking about old MK fans? I'm sure you know who ded_ is then. This is his video:
http://www.youtube.com/watch?v=t8h7raeObLA
I'll quote him:
yeah, 3 heads does not exist in MK1, whoever posted a video of it, is fake or made with cheat.dat file
3 heads is not wokring in t-units at least, dont know about earlier revisions
The author of the video you posted says he did it on t-unit last version 5.0.
The text "Cage Wins" just doesn't come late like in his video on any version
I don't quite think he did it like he says (t-unit, last version) He was IMO using cheat.dat or edit video. Again, I'd love to be proven wrong.
How hard can it be, record it with your cell, upload and post here.
I won't be debating this anymore, I don't think it's possible - prove me wrong.
The video you keep posting is not proof, for reasons already mentioned.