Some cameras can use 'phantom' power that is imposed on the RF cable itself, much like some microphones use phantom power.
The difference between the usable frequencies and DC power is so great that it is easy for simple RCL filters to separate the power from the signal at both ends of the cable, whether it is RF coax or 600 ohm cable with XLR connectors.
If the camera (or microphone) has no external power then it must have lithium or other high quality batteries that should be replaceable. RFID techniques only have a range of maybe 1 meter, and the RF power is very weak, even compared to Bluetooth.
