Well, I realize that 1970s sounds like an age of dinosaurs to some people… But, people back then weren’t cavemen. They had electricity, batteries, video cameras, telephones.
The concept of an electric outlet in a couch is easy - not sure, but they might even had such things back then. Like to feed a lamp or something. USB is just low voltage and different connector, from the power transmission perspective.
The concept of a speakerphone with video signal is also easy. The only thing to grasp is that the devices and batteries became that miniature and efficient. Oh, and wireless.
Explaining that all video and voice recordings from all these neat devices are actually stored by a gigantic corporation, processed with voice and face recognition algorithms, and used to enrich personal profiles collected on all parties of the conversation to boost profits of said corporations, and many people even pay for this - THAT I would find complicated to explain.
That would be $249.99 please