A small technical digression, if you will.
Jenkins and other mechanical TV inventors had systems that could produce about 30 lines (today we'd say 30 by 30 pixels) at around 10 frames per second. At those data rates (in the analog domain, of course) it translated into a bandwidth of a few kilocycles (Hz weren't invented yet <];^).
The good news: These primitive TV signals could fit into any audio technology: phone lines, mechanical records, and ordinary AM broadcast stations. All the early broadcasters of these signals did so on AM broadcasting channels with ordinary transmitters.
The bad news: The more clear-headed of the inventors, and I think Jenkins was one, knew that the system would have to tremendously improve its image quality before the public would accept it.
Two problems with scaling it up: First, they were tearing their hair out trying to do it; ultimately, they failed because the mechanical technology presented pretty much of a brick wall to significant technical improvement.
Second, they would necessarily give up all that cheap, easy-to-come-by storage and transmission. Because instead of a few measly kilocycles, they were going to need systems that could handle at least a megacycle, or five, for a video signal.
The electronic system proponents realized all this, and embarked on an expensive R&D program to make electronic TV work, with new and difficult technology at every point of the chain from the live image to the one in the user's eyeball. (The expense of the project at RCA gave Sarnoff considerable heartburn.)
So you had two competing systems developing: One, with near-immediate payoff but fundamental limits that would keep it from ever becoming a great commercial success, and the other that required a long and ruinously expensive R&D cycle but whose performance promised a chance of universal acceptance; a promise that was ultimately fulfilled.
I haven't looked into this much but a couple years ago did stumble across a website that had some animation video of a woman dancing or singing or something. It came from a record disc transcribed I think in 1922.
Even earlier I had stumbled on a book written (and signed) by Jenkins in the 1920s. He even included the plans so that readers could build their own receivers and report back what signals they had seen. The closing chapter was a study on the motion of a flag flapping in the wind, which gave him his answer for the film projector problem.