From what I know of the Khan approach, it's akin to "flipping the classroom" [0], which has gained pretty wide acceptance. It was pioneered by Harvard physics professor Eric Mazur.

(I use the flipped classroom approach extensively. But the legal profession being the eager embracers of novelty that we are </sarcasm>, I refer to the approach as "enhanced Socratic method," given that Socratic method was something we all endured in law school.)

For math and engineering courses, the basic flipped-classroom approach was used at West Point for over 150 years: In the so-called Thayer method, students study textbooks in advance, then in class, they work on problems on chalkboards. The instructor moves from chalkboard to chalkboard, coaching the students in real time. [1]

(I do much the same thing in my contract-drafting classes: In small groups, students do drafting exercises using online whiteboards. I lurk on my laptop, quietly coaching in person as needed.)

[0] https://bokcenter.harvard.edu/flipped-classrooms

[1] https://flippedlearning.org/syndicated/avoiding-flipped-lear...