The pilot was demonstrating emergency procedures and non-standard maneuvers in the helicopter to a new hire pilot and a company sales representative. After several simulated engine failures and autorotations, the pilot initiated a “quick stop” maneuver. The maneuver he performed did not comport with the published procedure in the manufacturer’s flight training guide, and in some cases contradicted the factory guidance in the pilot’s admittedly “slightly modified maneuver.” The pilot initiated the maneuver about 40 ft. above the runway with about 40 knots airspeed. He reduced throttle, which was not directed, added left pedal, which was opposite of that directed, the engine and rotor rpm decayed, and the helicopter descended. The pilot said that he could not recover the engine or rotor rpm prior to the collision with the runway, which substantially damaged the helicopter. The 3 occupants of the helicopter egressed without injury. The pilot stated there were no mechanical deficiencies with the helicopter that would have prevented normal operation.