The very first doubles I ever dove I assembled from my then-still-new Sherwood Genesis HP 80's (3,500 psig) to fit on my orange Scubapro Stab Jacket.
I had purchased some used SS tank bands that were made for Al 80's to be worn on a plastic backpack, I think. The bands had polymer inserts that fit inside them (to protect Al tanks from electrolysis, or maybe simply to protect Al tanks from scratches). The bands also had some little convex SS pieces welded to them intended to mate with the molded-in curve of a plastic backpack.
This was in 1989, I think, and I had not too long before returned from being cavern and basic cave certified at Ginnie Springs FL.
Anyway, I mounted both tanks in the bands the "normal" way (i.e., with the air outlet facing forward, valve knobs toward the diver's right when worn), bolted them to my SSJ, and mounted my two Scubapro Mk 10 regulators on them. Voila! Independent doubles!
I briefly practiced turning the valves on and off in shallow open water when wearing my rig when I was dressed in my 1/4" farmer John. No problem.
And then I went for a short dive in Roubidoux Spring (MO), my first cave dive outside of my basic cave cert course.
So much fun!
Okay. So what does this have to do with the video linked in this thread? Well, I wonder: If you have SS tank bands, why not use them (instead of woven nylon tank straps)? And why do you need to turn one of the tanks "backward"? (I didn't have to do this.)
Caveat: For any new diver reading this, don't do what I did. That was from an era when divers had fun experimenting with gear configurations. This is no longer permitted.
rx7diver