[danachow]

He’s demonstrating the use of a transformer to step up the voltage. The thermal properties are because of the lower current - not the line frequency. The transformer requires AC to work, but that is not the only way to convert power, and once the voltage is stepped up, it can be rectified back to DC and will actually be more efficient than AC - hence the reason that HVDC is a thing.

High power DC-DC conversion equipment is still more expensive than AC and the technology simply didn’t exist during the current wars.