I think that good videos add something on top of the raw script. Visuals, body language, sound effects and music, timing,... That's just for the kinds of videos where the bulk of information is in the script, which excludes things like videos about music production or the like.
Maybe if you spend 20 minutes reading a book, there's going to be a lot of interleaved information: kind of repetition, but with change, so that you really get a good feeling for the core ideas.
A video that would take the same amount of time to watch might not have the same density of language (and I'm not even sure what the ratio would be: i don't think it's 10X, as you implied)--well, maybe it achieves a similar effect, that of increasing comprehension, not by repetition or extra examples, but by the non-linguistic information I listed above.
The 2 minute article just doesn't have the same sticking power.
