He doesn't do a lot of the new videos. It's lovely to hear his voice when he does, though. Makes you feel just a bit more special.

Perhaps Sal doesn't have a great understanding of cryptography? He doesn't do a single cryptography video on khanacademy as far as I know.

Sal still makes lots of videos! Lately he's been making a World War I series:

https://www.khanacademy.org/humanities/history/euro-hist

We just like to put up good content from other authors too when we find it. :)