I've seen videos on Youtube, and most are good as a general guide, but none go into the level of detail afforded by a one-on-one (ok, 1-on-5) class.
Little things like the direction in which you should pull your thumb across the edge of the blade to check for the burr. How to ameliorate if you've managed to form a burr on all but 15% of the blade edge. How the colour/reflection of your honed edge should be consistent along the entire length of the blade - stuff that is generally too fine for a camera to pick up on. The sound made by the blade against the stone when material is actually being removed from the blade, as opposed to the futile rubbing of metal against stone - too subtle, I suspect, for most microphones to pick up.
To sum up, without stating the obvs. I think a video would be hard pushed to match that delivered by a well tutored class.