I'm a high school student, and I think Khan Academy is a great idea, except there's a fault preventing me from using it more.
Often I find myself on Khan Academy searching for further clarification of a concept, but the 10 mins videos are difficult to sift through, plus they usually start teaching from the very beginning, while I already know the basic concept and am looking for enrichment, just distilled information.
I think video format is great for self-learning, but not as much for a classroom supplement. I do not have time to go through an entire unit's worth of videos to find the piece of information I'm looking for. Articles are much faster, I can skim through them quickly until I find what I need. It enables easy copy-pasting as well, for notes or googling.
Right now I go to random websites more than Khan Academy, and I think this is a shame because KA's information is much more organized and centralized, but the video format just puts me off.