A BBC Science Show Introduces the Moog Synthesizer in 1969
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https://www.openculture.com/2023/10/a-bbc-science-show-introduces-the-moog-synthesizer-in-1969.html
Here's the main video if you don't want to read the article.
There's actually a surprisingly good basic description of subtractive synthesis(considering how new it was) as well.