George, you have summed up the situation perfectly.
I am in the same situation, a professional turner teaching and doing demonstrations, as well as a club secretary, so see both sides of the 'costs' argument. What other form of entertainment can be got so cheaply!
And I agree with several other posters that the interaction with an 'on site' demonstrator cannot be beaten. You need to ask questions AND get the answers, as and when they occur, and, although it is technically possible, I don't think it practical to use the internet for that purpose, for a host of reasons.
I will throw in one more thing to consider. If we go this way, there is no need for clubs to meet and you lose all the social side. Woodturning can be a 'lonely' hobby in so far as you don't need a team of people to take part, so clubs provide that interaction with other people that keeps us all sane.