Witnessed animal abuse

I was working on a girl's computer (trouble shooting Windows etc..) and I did a search on her computer for *.AVI basically, movie files as I was hooking up security cameras to this computer. Long story short, I came across several clips of videos with this girl in them. The first video was of her in a truck in an empty parking lot, video camera was setup at an angle so that the viewer could see into the driver side door, the ground and the front tire. At first, all I saw was this girl slowly driving her truck in reverse, but paying close attention to her front left tire. Door was open and she was looking down, almost as if it appears shes making sure her tire is rolling over something. I then advanced the video and see a close up of the tire and I see what appears to be hamburger meat or something, tire was all red stuff smashed into it. So i backed the video back up and watched again, low and behold I saw something squirming around. Guess what it was...3 live, white mice duck taped by their tales to a piece of wood. This girl was casually running over these mice that were alive, hence the hamburger looking meat on her tire. At this point, I am throwing up in my mouth, but trying to contain my composure as not to let this girl know what I saw her doing on her computer. I then look at the other videos that were similar in nature, the titles of these videos were things like "cut in half part 1 of 3, not sure if you saw this" of course, i'm curious and I look at these videos. Same girl, sitting on hard wood floor, mice duck taped by their tales, this girl has scissors in her hand and is cutting the feet and hands off of these mice, and then holding the feet and hands up to the camera by the scissors. Ultimately, she ends up cutting the mice heads off with the scissors. Trust me, even typing this, I am on the verge of throwing up, I cannot believe I witnessed this shi*. Last but not least, the last thing I saw wasn't a video, but a still shot (picture) of her foot with shoes on, smashing 2 mice between 2 pieces of wood, there heads hanging out, apparently, she stomped on the wood which decapitated the mice. Please someone, help me, help me understand what the F is going on in this persons mind. She said she did these things for money from some guy off the internet. She never even got paid for doing these things for this guy, but what type of person can calmy do this stuff ? She said she was acting, if she showed any expression in her face, the videos wouldn't sell and he didn't want them. Please someone respond...what is going on here?