* Khan makes mistakes and just leaves them in.
* Khan doesn't tell you how you could use these things in real life
* He's just using a procedural rule-based approach.
Um, did none of your school teachers ever make those mistakes!?!? Because mine did, all the time. And I had nowhere else to turn. The beauty of Khan, and all the other educational videos on youtube, is that you can get a second (or third or fourth or tenth) opinion on the matter by asking your school teacher or by doing some more google searching. This is amazingly better than it used to be.
The great thing about Khan is he's obviously having fun teaching you. He's laughing and having a good time, he makes little mistakes and he has to scribble things out or correct himself later, and it's OK. He draws in pretty colors. What does that convey to a kid? Math can be fun! There are people that like it! You can like it too! It's OK if you mess up, even the pros do! The first time my kids watched a Khan video they were simultaneously cracking up and getting excited about their new-found knowledge. They begged for more. It was awesome. I wish more teachers taught like Khan.