I agree with you, I think you've explained it well, I think many other people in education are thinking along the same lines, and I think that's sort of the idea with Khan Academy, Vi Hart, ASAP science, and all those other youtube things with fast-talking voices and sketches. The whole process could definitely do with a little more up-scaling, budget, and legitimacy as a lesson plan.

What you (and many other folks in education) are talking about is basically the function that textbooks fulfill- it's just a matter of incorporating new media.