Thanks for the video link, ORAC.
Starting at about time 12, it looks to me like a couple of chaff/flare launches were made, then a flash in the vicinity of the Tail Rotor/Tail Rotor Gear Box. Didn't see any missile smoke trail, but perhaps one hit it after the missileboost phase was over. (Chaff/flare launch due to smoke seen?) (Could also have been well aimed fire from a AAA unit, but my guess would be missile). After a few more looks, maybe those flashes were other hits on the helicopter. Grainy video.
Again, it was hard to make out detail, but the nose pitch down moment looks like the tail rotor and its box came off -- a significant CG change happened. (One cannot be sure if any flight controls were damage by what hit the helicopter, or if the crew were also hit with frag...).
The rotating descent further suggests to me loss of the tail rotor, though what other controls may have been damaged is hard to say.
Tough one to try and salvage. .
EDIT: after looking at that frame by frame analysis provided in downsizer's link, it appears that my guess at a chaff/flare launch is wrong (right before the tail was hit) and that even though the initial report was that the helicopter was out of ammo, the video seems to show it using forward firing ordnance shortly before being hit in the tail. Looks like I get a C- for video analysis.