There is often confusion over this issue and it comes up a lot, so here are the key points.
If you use your car for business and have to claim for some reason, and you don’t have business cover in place (assuming the insurers find out you were driving on business) they may not pay out your claim. If you think you may need to drive for work at some point (recces, going to location, picking up props or equipment etc) then add some business miles to your policy. It’s quite cheap and it means that you are covered should anything happen.
Who or what you are driving and why is really not your concern. If the production company wants to put their talent in your car and rely on your cover that’s their problem, not yours. It isn’t up to you to insure the talent or the equipment or anything else. The production insurance held by the company will respond if the talent has an accident and is unable to continue. but with “business use cover” your liabilities will be insured and you need not worry.
Some people seem to assume you need to take on the responsibilities of the company and insure for having talent in your car etc. You don’t, although the insurance company may take the view that your job makes that a possibility and will take that into account in your premium calculation. All you need to do is protect yourself – just ask for ‘occasional business use’.
A word of caution though. IF an accident is your fault and IF you injure someone or damage equipment and IF you are NOT covered you could be in serious trouble – because the company may decide to claim against you for negligence in order to limit their losses. Without cover to protect you that might well be a major financial disaster for you. So get yourself covered.