YouTube is great for things where the directions for the specific activity you want might not include "basic" things someone who knows it well wouldn't think to list in written instructions, or some little technique or movement they do automatically and don't even think about. I love it for house and car DIY stuff, for that reason and also because it makes it clear which parts will be a pain-in-the-ass, and how much, to help me gauge whether I want to do it, or hire it done.

It's also great for technique with tools in the kitchen—not learning recipes so much, but learning the right way to process a certain vegetable really fast, or exactly what a proper whipping motion for eggs ought to look like, or how a pro moves the pan on and off the flame while cooking this dish, exactly what it looks like when they deem a certain cooking technique "done", all of that.