For those who have not heard of Khan Academy, please go here -> https://www.khanacademy.org/
Salman Khan, who started the Khan Academy, created the first few videos for his nephews who were living on the other coast of the United States. He found that, explaining concepts over youtube videos was much more easier, and that his nephews found it way more productive learning from them. There are several reasons why and if you want to know more, you should hear his TED talk.
Long story short, he started finding that, folks all over the world, on the internet, started loving his tutorial style short videos. He now runs this as a non-profit organization. He also has a learning framework that he is experimenting with, in the public school system.
The best thing about a Khan Style Video is its brevity, its clarity, and its simplicity. So Khan’s mentor (his professor at MIT) Anant Agarwhal asked him to do a KSV on how to create a KSV. And in his own words, Khan says, “he does a best effort in trying to accomplish this very meta level task”.