I first got interested in and learned to cook from cooking shows (Alton Brown, Emeril Lagasse). Of course I had to do my own cooking, but watching them made me realize it wasn't so hard. I'm a shade tree mechanic, but without the service manual, it's helpful to find a video replacing whatever part I'm about to deal with for the first time (Chilton manuals are crap). A few years ago I needed to pull the double-oven out of my cabinet to replace the heating element... I'm sure glad there was a video for that too. What's the right form for a kettlebell swing or a push up? How do I tie that knot again?

Yeah, there's lot of junk on YouTube. You might even say 90% of it. But there's tons of useful content too if you go searching for it.