And regarding the mention of an old book about a future in which one could record one TV show while watching another: Videotape was developed in the 1950s, when few people even had TV sets. It was used as a relatively inexpensive film substitute for TV stations. Reel-to-reel video recorders became available in the late 1960s, but I don't know if they could be connected directly to TV sets and record off of them. The first videocassettes appeared in the 1970s, but few people had them. (The cassettes were huge, too!) VCRs for the common folk didn't show up until the 1980s. But some of that technology was in existence for a long time, fueling the imagination of those who were familiar with it.

For an example of some more prescient technology that only recently became available (and still needs work before it becomes commonly accepted), check out Fritz Lang's 1927 film "Metropolis." We see a videophone that allows the autocrat Fredersen to communicate with the workers' foreman and see him at the same time. (The foreman, being of a lower class, does not have a similar screen at his end of the line allowing him to see Fredersen, however.) In 1927, television was still largely theoretical (although some closed-circuit TV experiments may have been done), so this was an astoundingly high-tech gadget at the time.

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