I watch videos of fat people to motivate me when I work out
Is it because you feel motivated?
No, I enjoy watching them and it makes me laugh
You definitely don't want to get fat, so it's good you're working out. Watching the videos just for laughs is a bit odd, though.
There are so many fat people it's not right. I enjoy making them look silly. People need to lose weight so people like me don't laugh at them.
People might find it really hurtful if you make fun of being fat. They might want to avoid you if you come off really hurtful.