Besides gory video games I find none of those interesting, so I can only hypothesize on those. Gory video games are just...fantasy...they over exaggerate most of the time so they aren't even that accurate, same with gory movies. For me it's just the rendering, like an eyeball flying at you with a trail of blood. In real life that wouldn't be so amusing. It's like living in a world of the what if, letting your inner psycho out for a bit. When it comes to gory games I stick to Resident Evil, those are mostly zombies and creatures anyway.
The rest of the stuff, I dunno. Same thing I guess. The stuff that is real anyway. It's someone else being hurt too, not yourself or someone you really know most of the time. People usually cheer them on when they don't know them. It's like releasing some frustration vicariously. I imagine those who know the person who is in a fight are all like "are you okay" afterwards. While others who don't would be like "did you see that guys tooth go flying out of his mouth, that was awesome".
Interesting question, I've never been in a fight or watch that stuff. I've seen fights at school but usually walked away most of the time. I'm not big on violence except for the fake staged stuff like in movies and video games where no one gets hurt except by accident if that.
