The flight departed Birmingham airport with a VFR clearance for a local photo shoot. The helicopter was flying above a ridge line and made a right turn into a hover. At this point it began to rotate to the right about the main rotor shaft, and spiraled to the ground. The pilot stated that there was no mechanical malfunction, and the helicopter had lost tail rotor effectiveness. Examination of the wreckage revealed that the tail rotor drive shaft had broken in overload.