I found a couple of short clips of Hal teaching the 2 on 1 grip to the geriatric crew plus one young marine DT instructor. The dojo is Parker Linekin's Academy of the Maqrtial Arts in Mira Mesa, CA (2005).
Here is the 2 on 1 grip with foot sweep.
and another with an ikkyo-style arm bar much like what was posted earlier.
and a clip where Parker Linekin and I are "rolling" with a series of grips and counter grips demonstrating how to get into the 2 on 1 grip from a traditional attack. Notice that we never allow a full 2 on 1 grip as we are assisting each other to become fluid in transitions.