A high school student I know finds the Khan videos not deep enough. She said they are a good introduction but didn't cover anywhere near what she was seeing in class. So I guess you get what you pay for.
If she just wrote to Salman Khan along with classmates, i am sure he would be happy to cover the missing areas too.
It's just that he chooses areas to cover based on feedback from students/users - and if enough students approach him, the subject gets magically covered.
