Seriously... why?

I signed into blogger with the intention of blogging about stupid questions people ask but a more pressing issue has come to my attention.
So I was on youtube and one of the guys that I'm subscribed to (Ksicsfaces) linked this video in an attempt to raise awareness about animal cruelty:

http://valleywag.gawker.com/5626105/4chan-on-the-hunt-for-puppy+throwing-girl

Before you click that link, I suggest you make sure you're prepared to see it. Basically it's some girl who is throwing puppies into a river where they die a slow and painful death. Seriously.. what the heck? What do you get out of ending the life of an animal that has barely had time to live? What satisfaction is there in knowing that you cut short the life of a perfectly innocent puppy? What on earth was going through this girl's mind?
I'm one of those people who thinks that animal cruelty is about as low as you can get. Watching that makes me wonder why? I.. can't even think of how to word htis but mainly what's going through my head right now is WHY? WHY WOULD OYU DO SOMETHING LIKE THAT? Who wakes up one day and thinks "oh Im bored lets go chuck some puppies in a river and sees what happens" Ok. To be fair it probably didn't go down like that but no matter what went on in her head I don't think anything is a good reason to do something like that. Nothing gives people the right to act all high and mighty to helpless puppies.
Gah. I cannot get over it. WHO DOES THAT? IT DOESNT MAKE ANY SENSE. GRRRR. Ok I am calm and composed :) -end rant-