Well, that's the specific example, but there exist a class of educational blocks such that the learner doesn't know where they're stuck, because if they could define it, the act of correctly defining the stuck step would inherently unstick it.
So MOOC strategy works for some areas that don't have sticking points like that, but not so well where five minutes with a Socratic strategy tutor could save a lot of video re-watching time. Arguably, better video would point out likely sticking points. However, advanced math instructors got their position not by getting education degrees which theoretically vocationally train people to present like that, but got their position by being very successful when getting a PHD in an obscure and advanced part of the field. So if you're lucky, your higher math instructor might be a talented educator in addition to being a talented mathematician... but probably not, unfortunately.
It would be interesting as a thought experiment, or maybe as a startup, to see a good (emphasis on good) K-12 math instructor with a strong background in educational teaching skills try to teach diffeqs or higher math in general. I suspect they'd be extremely good at it, although probably very slow.