Just some late night hunting, Leaf style. Without going too far into spoilers I'll just sum up what this scene would be for people who only played up to this point. Key words UP TO THIS POINT. Try and understand what this means for those who have played through the entire game and are intending on arguing with my summary.
Basically the protagonist transformed into a monster and went "hunting" in town against his will.
Quick sum of events:
Shortly after he came to, the "Monster" spotted someone coming home from the convenience store and leaped at them, you can figure out what happened to him from the effects. Then the rest of the video is pretty much the same. Spotting someone--Leap--Destruction.