Is this safe? Is his head okay?! Why would you do that???
One friendly commenter on Reddit attempted to offer an explanation, for those of us who are confounded by this scene:
"The thing about burning hair is it tends to only burn small spread out amounts. So a clump of hair won't burn but stray hairs will. So for her the dreads occasionally get frizzy; you hold it vertical and light the base near a wetted scalp. The whole thing goes up quick and then burns out just as fast. All the frizzy, dry, split ends that are stick out burn off."
Other hypotheses include choosing this process because it could create a more natural and less clean-cut feeling like what one would get with scissors, or it could be a method of reducing volume without significantly reducing hair length.
That said, PLEASE don't try this at home!