Record Making with Duke Ellington

"This promotional short for Irving Mills' short-lived Master and Variety labels not only gives us a glimpse of Ellington and his band in the actual Master/Variety studios (as opposed to a soundstage set), but is one of the very few film accounts of how records were recorded, plated and pressed in the long-ago age of analog, shellac and 78 rpm. Narration is provided by pioneer radio announcer Alois Havrilla."
Record Making with Duke Ellington, 1937:

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Note: also see this post for "How Vinyl Records Are Made" (with a little more modern touch)