Yup, I know exactly how you feel. I'm always livid when watching those things. It really does illustrate how cruel people can be, how cruel and unthinking.
You know, it could be worse though. I was at my cousin's house for xmas last year (now mind you, he's 25, not a 14 yr old). He waved me over to the table where he was looking at things on his laptop. He said, "You want to see something cool?"
I replied, "Sure!", thinking I'd see a goat riding a horse or something. No. Instead, he showed me an al quaeda video of this white guy getting his throat SLIT OPEN! Cut, with a dull knife. Sometimes, when I am trying to fall asleep at night, I still remember his screams, loud and then immediately muffled, like coming from a far off place.
Sorry, I don't know why I digressed, but even cruelty as small as an animal devouring another at the hand of their master, or a person dying makes me sad, angry and confused about whether our species is one that deserves revelry or the severest of punishment. It makes me pull my hairs out.