Don't forget, Daniel, there have been about 20 members of ABB over the years. That clip is the 1980-82 line-up. Jaimoe was fired in '80 & replaced by David Frankie Toler until the 1982-89 hiatus. Also included, besides Gregg, Butch, Dickie & Rook, were Dangerous Dan Toler (long-time & still Betts collaborator) on guitar & Mike Lawler on keys. Big Al Glisson also played guitar with them in this period, but I neither see nor hear him in this clip.
Peter