The internet is an amazing learning tool, and the amount of information freely shared by others is remarkable. Apart from saving $$$ by learning how to DYI, it's just a great feeling to know you can learn to be self sufficient especially in this age of commodified convenience. What are the most interesting or useful practical skills you have learnt online from YouTube (or other freely available resources), and wouldn't have if YouTube were not around? I've learnt how to fix all sorts of electronics and my car. The other day, I had a go at cutting my little brothers hair and did a pretty decent job I must say!
Probably learning how to program (or at least part of my learning). And that probably going to be my job in a couple of years.
Thanks to Youtube, I finally got the air bubbles out of my screen protector. I also found a ton of download links to awesome software.
I've been trying to pick up a little bit of ASL and German. I am also learning to code, and learned a lot of my biology curriculum last year through YouTube. I also learned some knitting and crocheting techniques. Lots of miscellaneous stuff.
From simple things like properly wearing a tie to getting some IT certifications. It's a wonderful thing, YouTube.
Watching people's recorded speedpaints helps a lot with art and does wonders for inspiration. I've learned a lot of the Adobe Suite and tons of stuff involving computer software such as using Terminal, editing the registry, etc. I also use it to regularly watch things in German to help me practice.