Looking at the roof in the video, I'm going to speculate.
This was a successful autorotative forced landing. At the last second the pilot realised he was coming into a roof and not the ground, and flared and pulled hard to get a few feet of height. With nose high and NR low the tail boom impacted first - note the small hole in the roof to the south of the big one - which damaged the the fenestron area, then the aircraft ran on its skids for about 20 feet, trashing the aircon unit on the roof as it went (loook at the trackmarks on the roof) which did some damage to the underside, before the roof collapsed under the increasing weight as the last of the Nr vanished, the aircraft tipped sharply nosedown and with at a guess about 20kts forward speed smacked hard into the end wall. That is not a type of impact that aircraft are designed to resist.