I haven't checked out Coursera, but isn't it more of a college course that you can take online? Khan's videos seem much more accessible and are mostly aimed at a high school level. There are many people who browse through Khan's videos who don't have the time, motivation, or ability to take a Coursera course.

I think that basic computer science (or at least basic theory of computation) is at least as important to understand in the modern world as algebra or calculus, and I don't like that it isn't more widely taught. I looked at Khan Academy hoping to find a good introduction for someone and was disappointed when I found that all it had was an introduction to programming.