>Salman Khan, uses positive and negative signs inconsistently and mixes up transitive and associative properties.
Oh, the irony: Khan actually confused the commutative and transitive properties. The parody video gets it right: http://www.youtube.com/watch?v=hC0MV843_Ng#t=3m14s
This stuff is hard. To be fair, I don't think Khan is doing any worst than a first-year teacher in his first class of the day.
Youtube provides annotations – I wonder why KA doesn't insert crowdsourced corrections the instant a mistake is made? It seems like a good middle ground between his "write-only" philosophy (which has made him incredibly prolific) and the legitimate criticisms that quality has suffered as a result. This video was corrected, but I'm sure there's countless other small mistakes that could benefit from a change in process, not just a PR band-aid.
I've seen quite a few of his videos that have had serious problems in them, 20-second long stretches of silence when he's erasing or fixing mistakes, and places where he talks himself (and the listener) into a circle. I just don't see why Khan doesn't take the time to fix obvious mistakes/issues in his videos -- or have someone else do it! Sure, it means more video development time but it's for the purpose of producing superior lessons and not spreading misinformation.
Traditional educators revisit topics/lessons and learn from their previous attempts and from student feedback. This allows future lessons on the same topic to be more refined and better serve the student. Who honestly believes they get something right the first time, or doesn't try to improve something when they, or someone else, identifies an obvious problem?
Khan has an excellent framework in place, but he needs to revisit his content. Or let someone else do it -- do these videos have less value if someone other than Khan comes in to fix things up? I'm sure there would be plenty of volunteers. Obviously the guys in this video had some good insight that could have helped Khan's video.