Holy crap! That guy is....

DIZAM!!!
For those that don't get it, to do a counter in that game, you have to press forward EXACTLY when you're about to get hit. If you screw up the parry, you take full damage. Blocking is easier, but you soak up some damage from the attack.
"Uh, doesn't blocking just involve holding the back, ala SF2? It doesn't seem that amazing, since he gave the guy like, 10 seconds to do the super move."
That's just it, he wasn't blocking at all. If he had blocked, he would have died. Basically, he was hitting forward repeatedly to counter every hit of Chun-Li's super attack with perfect timing.
Wow, I'm still in awe. Watch the mini-window of the player on the right when he gets owned at the end. You gotta feel bad, but you gotta repsect the guy playing Ken for knowing the game that well.