There is always a chance for pilot error, mechanical failure or some dipstick interfering. I found a company called Risk Transport that insures quads and such. Filming weddings or cinematography could pose huge risks. Any thoughts?
Sure - if you have assets to lose, you want to make sure you are covered in some way. An umbrella policy is always a good idea in addition to others. That covers things that no one thought of or over and above your homeowners and your other policies. Amazingly enough, even your homeowners policy can partially cover you against liability in other places. I know someone who got in a bike accident (two bicycles) and the other persons homeowners paid for fixing up my friend...even though they were many miles away from either home! I think the AMA also provides insurance for member - but it's unlikely that covers quasi-commercial work.