First, here is the film we began to watch about how records were produced at the RCA Victor plant in the early 1940s:

https://www.youtube.com/watch?v=qZ5PQSaDYgU

Also, here is a short film you might enjoy about what happens when a recording medium (an LP, a CD) is read (by a stylus, or a laser). (You can also read the short accompanying article here.):