I think everyone should watch it so if we're having a bad day, we can remember that this man had it much worse and he stayed strong. I think it could also to make us aware that there are evil people amongst us.
I really don't know how a person could do that to another human being. If you have a desire to cause that sort of harm to someone, you should pray to Jesus to take the malice away. You should also call the British Samaritans, dial 116 123 and speak to someone for free that doesn't know you and figure out a way to disguard those hateful thoughts.
I guess if you're a psychopath then you can't help it, only Jesus can help you then.