Far be it for me to defend Zinsco crap, but nothing on that video showed me anything other than a couple of loud nincompoops playing with fire. If they wanted to impress people, a diagram or explanation of the "test" circuit and a meter showing the actual current going through it would have helped. All I saw was a wire glowing red hot. Was the current really passing through the breaker? I couldn't tell what the "load" connection was. Looked like maybe they just grounded it to the box? Was the box solidly grounded or maybe there was a high resistance there? Why didn't the feeder breaker trip as well?
The comment at the end "Is there still power going through it?" after they turn off the feeder to it leads me to believe these were rank amateurs.
I know a guy who has designed and built a line of Zinsco replacement breakers and interiors (the interiors were just as suspect as the breakers themselves). He designed the breakers so they can't be plugged into old Zinsco interiors and his interiors will reject original Zinsco breakers. But they drop into the exact same mounting arrangements in the box and the old trim fits so the walls don't have to be wrecked. He got the entire product line UL listed as a drop-in replacements to existing Zinsco panels so that contractors can do a "1/2 hour swap out" by configuring the new interior exactly as the old one is, removing the wires, dropping it in and reconnecting the wires. He can't get funding to mass produce and market it because nobody will touch anything associated with Zinsco with a 10ft pole.
