liability on the GC is huge should the authorized site visitor be injured or killed. i've seen contractors who will halt all work in progress whenever an improperly attired homeowner or other visitor is on site and even walk off the job if one wanders around unaccompanied and not wearing the appropriate safety attire or fails to follow instructions. the GC has a responsibility to secure the job site and safety. i guess that TOH productions has some type of overall hefty blanket liability insurance for their project sites should their production activities cause a hazard or injury including their filming with home owners on site during work tours and things like kevin walking under a boom during craining operations. they probably have the homeowners sign some type of imdemnity waiver that their lawyers or insurance company lawyers draw up.