The airline transport certified pilot was operating his dual turbine-engine helicopter near a 14,110 foot high mountain in order to film an automobile driving up a road. The pilot stated that he had operated around this particular mountain several times a year over the past 24 years and had established a flight profile which minimized the associated risks. One sharp turn in the road near the peak required the pilot to fly outbound from the mountain and make a gentle 180-degree turn back to film the automobile. When the pilot flew outbound from the mountain the flying conditions were normal. However, after turning 180 degrees and on the inbound leg towards the mountain, the helicopter encountered a downdraft and was pushed towards the rising terrain. Helicopter performance at that altitude did not provide the pilot with a power margin great enough to "power out" of the descent. The pilot elected to perform a landing to the road rather than risk a turn down the rocky mountain slope. The helicopter subsequently touched down hard and rolled over coming to rest on the left side. The helicopter was substantially damaged and the pilot received minor injuries. The three passengers were not injured.