Incredible save but not due to half the rotor disc being in ground effect.
He was approaching into the wind and by looking at the dust the wind was strong. He had to first contend with it strongly flowing upward to the left of the video and down to the right. His near-fatal mistakes began with picking a landing spot that would have been tail high into that wind. Next was the final turn to try to depart downhill by pivoting to the right, which would have required more power in that model (Huey 2) going to the tail rotor from what was available to go to the main, so he suddenly was running out of power and moving vertically down. Then he didn't use enough (or ran out of) aft stick to stabilize prior to actually touching down.
btw - This is what HeliMark used to do for a living.
Signed,
Checkswrecks
Great explanation, other than to add, he did not have any ground effect, you can see him trying to turn (and losing control) just prior to the ridge line. What Bob said about lack of, or not using enough aft stick, with his higher approach speed, he had to use a lot of power to stop and land, so what, if any power he had left wasn't much. He made a number of mistakes on that approach. First would be, in high winds, never approach a ridge line at a 90* angle, always approach at a 45* angle or less. This will give you the option to abort the approach without having to turn much, and if out of power, a simple nose dive with room under you. He should have had a steeper and slower approach in those higher winds. Another possible save, depending on where he started to lose it, would be to lower the nose slightly, and continue straight ahead. The helicopter would have picked up speed, reducing the decent rate, and as soon as he crossed the ridge line, he would have picked up the updraft.