The derailment was the center post on the rear truck sheared off on the plow
I have now modified the plow with a body mount Kadee, and a metal post with a screw going all the way through the body to keep the truck/bogie in place.
While apart, I changed the light to a bright white led.
Gotta love the better resolution of the blip.tv site.
Video was taken with a digital 8 megapixel camera set to 640 by 400.