Rastafarians take them seriously, it’s the biblical injunction not to cut hair that some religions share. But dreadlocks have been appropriated by many people, including Jamaican people who aren’t Rasta and a whole heap of modern hippies. And hippie-wannabes, for that matter.
Anyway, Rastafarians aren’t the first people to wear the hairstyle, men from India, Eqypt, Celts etc all wore them at some point too.
The video is kind of dumb. It’s one person picking a fight with another person. So the heck what.