Re: camera man: I suppose the question is how far do you want to take it. There are certainly things that could be done with a separate camera man that would add value, but if I recall the demos at our club (same as phil stevenson) most people watch the screen (more detail, bigger picture) with the camera not moving around too much. I guess in the end there will be some demonstrators who will hire a hand for the day (or evening), possibly their partners, and if they get it right, this might be worth a little extra.
I think the real benefit is in being able to see demos from places that would otherwise be inaccessible due to excessive travel costs.
BTW, there are lots of companies offering webinars on a similar basis: the teacher/presenter is available, with 2-way-communication, via the internet, and you can connect to that session (after paying your fee). Connection breakdown is actually easy to handle: if the connection breaks on the demonstrator's side, he is liable. If it breaks at the spectator's side, it's their problem. Provides an incentive to get a decent connection.
I don't see this completely replacing traditional demos, but it would certainly open up possibilities that otherwise are just not there.