In the site's current form, I think the fact that a viewer of any age can watch a history video is actually a bit problematic.
For mathematics, all of the material is broken down into the very basic components, so it's easy for a video to have a set of prerequisites which any viewer should understand before watching (with a set of links to the videos corresponding to those prerequisites).
For a subject like history, the material can't easily be broken down. As the article points out, a statement like "as you can imagine, Japan did not produce a lot of its own oil" may be common sense to someone of high-school age, but an 8-year old may have no understanding of how oil is produced or where it comes for and the statement may make no sense. This doesn't render KA as dangerous or useless, just points out a problem which needs to be solved and which they are certainly aware of :).
To me, that a viewer of any age can watch is practically the whole point of Khan Academy. Kids learn at different speeds and are interested in different subjects at different ages. Whatever subject you're talking about, there are some 8-year-olds who could benefit from it. The traditional approach of having grownups decide what material is suitable for what age is guaranteed to produce a mixture of kids who are bored and kids who are lost; khan materials present the promise that kids might be able to learn at their own pace and according to their own interests. The ones who find history of X fascinating will race ahead and do related research and file info away for later; the ones who lack context will probably be bored and lose interest and want to study something else and that's okay.
For mathematics, all of the material is broken down into the very basic components, so it's easy for a video to have a set of prerequisites which any viewer should understand before watching (with a set of links to the videos corresponding to those prerequisites).
For a subject like history, the material can't easily be broken down. As the article points out, a statement like "as you can imagine, Japan did not produce a lot of its own oil" may be common sense to someone of high-school age, but an 8-year old may have no understanding of how oil is produced or where it comes for and the statement may make no sense. This doesn't render KA as dangerous or useless, just points out a problem which needs to be solved and which they are certainly aware of :).