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A similarly interesting video in this pedagogical style is 'Around The Corner - How Differential Steering Works (1937)': https://www.youtube.com/watch?v=yYAw79386WI

Another archaic technology is magnetic amplifiers. These were more used in Germany (in the Kriegsmarine and also in the V-2), but got some more play in the US immediately after the war, before being largely supplanted by transistors.

The idea here was to use magnetic saturation to modulate the behavior of a transformer, allowing a small control current to modulate larger AC currents.

https://en.wikipedia.org/wiki/Magnetic_amplifier

the current 'click and subscribe' universe!

The audience for this film was heavily advertised to, in order to get them to subscribe:

https://fr.wikipedia.org/wiki/Fichier:Untitled_%282%29World_...

And if that didn't work, many were simply coerced into it by the state. You don't need to pester a captive audience to smash the like button.