Apparently the rules of this speedrun were to kill every Hunter in the game as quickly as possible; starting from the first level they appear in, Truth & Reconciliation. As soon as he kills the last applicable Hunter in the level, he quits and moves on to the next one.

It could still use some work, as there are a few pieces where he gets distracted, but there's still some epic K/M action going on, and it's still an interesting twist on the speedrun genre!