Funny but not so funny

I was watching Americas Funniest Video the other day. There was this clip in which the caged monkeys starts to attack the people outside. I can't understand why this is so funny. First of all you start to make all the funny faces at them and tease them. So they get all agitated.
If they attack you that becomes funny??
I remember when I was in class V we visited Chandipur from school. In the hotel campus they had two monkeys caged. We were as usual teasing them and playing them. And one of them did attack me. Fortunately, I was not injured. But, my new dress was ruined.

The attack made me think that why did the monkey reacted in such a way. He is also sacred by us as we are. It's just that we are free and they are caged.

Onlookers may find it funny because that attack has not happened on them. In fact they are relieved that I was not in his/her place.

In Americas Funniest Video, someone is either falling down or getting hurt. Is that there sense of humour? People get hurt and they find that funny.
Amazing concept of being funny.