I know A LOT since I've been on YouTube. It really is a great video site. Can YouTube make you smarter?

If you're learning something by watching it, then yes, you're getting smarter. Becoming smarter means to learn continuously.

I do have to question what YouTube could teach you though.

I'm going to disagree. Being smart is something that is a part of you. Watching YouTube videos is not going to make you smarter.

However, accumulating knowledge, learning things will help you deal with the world at large. The saying goes that knowledge is power. It's actually the guiding principle behind this site. When you learn you are improving yourself.