Roy Harris is a very interesting black belt. He wrote a nice "guide to belt levels in jiu jitsu" that was posted over at bjj.org back in the day, and remains one of my favorite belt-by-belt breakdowns explaining what those training in jiu jitsu should focus on at different levels in their development.
These are a variety of mount escape techniques from Harris that I found on You Tube. Some of them remind me of the sort of tricks that Cindy has talked about, attacking the legs as a way to set up an escape or a sweep.
Footdrag Mount Escape
Low Single Mount Escape
Footdrag Mount Escape #2
Foot Turn Mount Escape
