Ok I guess I can tell you now . . . .
The accident happened in Valle de Bravo Mexico, it took place during the filiming of a TV show, the actor was told a million times to position the rope so that it would drop under the belly of the helicopter and that under any circumstances not over the skid.
So he did just that the first few times, it had been rehearsed and done like 5 times before without a problem, but on the last take the actor left the rope over the skid with the resulting dynamic rollover.
Tha pilot was VERY experienced, he had flown with Swarzenegger, Stallone, H. Ford, VanDamme, DiCaprio, on the filming of many different movies that have been filmed here.
You can see some eye opening footage of the work this pilot had done here . . .
YouTube - Filmación Aerea