I still believe there would be no recognisable helicopter left if the drop had been very significant . Also I believe it would have been very unlikely to hit the roof the right way up . These things all point to a workable auto to a level not much more than 50ft or so , in my view . How do you explain the first impact that brought some ceiling down prior to the main impact some seconds later ??
Folk here posted some excellent YouTube videos of crashes, some 'real' and some trials. Helicopters are remarkably resilient, it seems, and if they land on the skids, those open up absorbing energy, then the fuselage crumples, again absorbing energy. In this tragedy, the roof also gave way and that would also have absorbed energy...the eggshell effect. From the description given by a builder, earlier in this thread, who explained something of the probable structure of the roof, I think it'd be very hard to estimate the consequences of any particular impact velocity but from the photo evidence a lot of energy went into the structure of the building, not the airframe.