fascinating video on tailplane icing

i stumbled on a fascinating video on tailplane icing at:

http://video.google.com/videoplay?docid=2238323060735779946&hl=en

from what i've heard about the recent accident it sounds like a potential culprit. one of the many interesting points is that flying on autopilot would reduce that chance that the pilot would "feel" any change in control due to accumulation of ice on the tailplane (horizontal stabilizer).
it's worth it to watch the entire video. at 15:45 minutes in, there's an actual tail stall during a test flight causing a pitch down that is clear evidence of a very dangerous situation for an unprepared pilot. this happened to a tail that had only a portion modified to simulate icing. i can't imaging how bad it would have been had the entire surface been iced.