A nice thought - and I am actually looking into this right now - but what about the screen capture programs that you just barely mention? More tedious? Yes. But doable? Yes.
Does screen capturing lose quality in the video? (Enough for surfers to notice?) I'd record my videos in super HD and possibly implement this... if it meant constraining an entire computer (video capturing) vs. downloading out of your cache and barely using any cpu resources PLUS a loss in quality I'd be very interested.
