Great question, Currently all model aviation enthusiast fall under the Academy of Aeronautics. (AMA) If you fly an RC aircraft with a camera or FPV (First person video) you are required to have a spotter or observer, fly under 400 feet, and within your line of sight. Not that everyone follows this regulation but that's what it is. Other than that there are no restrictions.
If you fly for hire or deploy a system as a government or civilian organization for inspections, surveillance, search and rescue, mosquito eradication, ect, you fall under the direct jurisdiction of the FAA to interact with their designated controlled airspace.
RC aircraft are supposed to be flow in designated AMA sanctioned fields and not over populated environment's. Again, not that everyone follows these subscriptions but that is the current legislation we all fall under.