Video: There's no such thing as useless knowledge — only knowledge that relies on very specific situations. Which is why, in the event of a horrible Mad Max future, you might want to learn how to make a bow and arrow using no modern tools whatsoever. Sure, making weaponry with access to a bandsaw, a lather or, hell, even some chisels would be orders of magnitude easier. And there's no reason to assume in a semi-apocalyptic event that any of those things would disappear (maybe electricity, but hey — chisels). The point is, Primitive Technology is really good at what he does and it's impressive to see someone make stuff the way your great-great-great-great-great-great-great-great-great-great-great-great-great-grandparents might have.
As a bonus he shows how to put fletching on arrows, and make a small quiver to hold them. Hopefully, the deer and birds of our shithole future won't be too irradiated to eat.