Matthias Wandel (https://www.youtube.com/user/Matthiaswandel) has a woodworking channel that I consider to be a massage for my brain. I know nothing about carpentry, but his videos are so relaxing.

I also like carsandwater for his "Red-Hot Nickel Ball" videos. https://www.youtube.com/watch?v=9qSEfcIfYbw&list=TLIZX0Wqcq2...

Numberphile has some great recreational math videos. https://www.youtube.com/user/numberphile

And, as a few others have mentioned, Veritasium.