I have seen the NASA tail-stall video, although not as part of official training for any aircraft I have flown (not even the DHC6!). I have NEVER heard of anyone having a tail-stall scenario in a simulator session...in fact I highly doubt that simulators are even programed to simulate them. I just find it way too hard to believe that in the heat of the situation that the pilots would decide to try to recover from a tail-staill when so much of their training would point them to other more appropriate recoveries.
I think this is the only time that people actually practice tail-stalls:
YouTube - Learning how to tail stall in stour-ramparts