Whatever happened to that Astar undoubtedly began well before the spin/crash. If you watch the the report that includes video from the accident ship, at about 2:00 minutes in, "something" happens and then camera snaps around to film backward toward the tail rotor. The aircraft assumes a left yaw/right bank attitude and continues flying, somewhat erratically. Around 4:50 the aircraft enters a left bank and it appears that it does a left 360 turn around the mast. But the pilot remains in control. You can see him get lower and lower, until it finally starts spinning and we lose the video feed at around 7:20. Time from the onset of the problem to the crash: a little over five minutes.
Switch now to the video shot from the other newscopter. In the first link, the video begins with the Astar arriving high over the site, and already rotating slowly to the left. It quickly picks up speed. While spinning, the ship begins droppping vertically, very fast. Maybe I'm wrong, but I think the puff of smoke from the engine comes when the pilot shuts it down to stop the spin. At the bottom, either he doesn't even pull any pitch or the rotor rpm has gone away and there's no cushion left.
Very sad to watch, and it must have been gut-wrenching for the crew in the other newscopter.
Maybe we'll never know why the pilot elected to do a landing in that small site with a tail rotor problem - instead of taking it to a bigger area or an airport.
Not every helicopter pilot is Chuck Yeager.