If you enjoyed that, you'll also like this BBC documentary (from 1987) on the history of recording:
https://www.youtube.com/watch?v=2IGyhXlDkL8 Not technical, but still a fascinating look at the inventiveness that's been part of recording from Day One. Check out the first dynamics control: the singer standing on a rubber-wheeled trolley that allowed the engineer to alter the distance to the recording horn - requiring the engineer to be able to read music and be physically fit (fortunately, both are no longer prerequisites).
Also the first "multi-microphone" recording machine, actually two horns at a 90-degree angle. And the first hit record (Caruso), which sold a million copies at a time when a grammophone was an expensive luxury for rich folks. Shows the beginnings of Abbey Road (1931).
Also reminds us that there was a time when listening to music was an actual activity, where people sat and gave it their full attention. Not much of that anymore.