I think video tours are a great innovation. I know quite a few Realtors who are using Youtube to show their listings. Most, if not all buyers these days are going to the internet before they even talk to an agent. The more information we can make available to them the better for both the client and the agent.
As far as why more agents are not doing it? It has taken our industry forever to get to the point where we are now. When you compare out industry to others and their use of technology and when they adopted new forms of marketing and information distribution, you will see that we lag far behind. Fear of the new, we are too bull headed as independent contractors, who knows?
But if you see something that can help your business, go for it.