I really wish I could tell you more about this guy, other than his YouTube handle -- "Amazing LP" -- and his excellent skills with After Effects. He also shows off a pretty mean set of special powers, including summoning machine guns, fireballs and various sharp implements to take out his 16-bit foes.
Posted back in November last year and apparently taking "more than 100 hours", according to the clip's description, "King of Fighters in real life!" is precisely what it says on the tin. It's a little more bloody than I remember King of Fighters being, but then, it's been a long time since I played.
In fact, I'm not confident I've played the game at all. At any rate, I doubt I'll have the chance to do it for reals, as Amazing LP does here. Even if I did, I don't think I'd be quite as capable with the uppercuts... or video-editing skills.