Well, I guess that it’s labeled FM because this filter will self oscillate and will track also 1/oct so together with the 1/oct input you get also FM like on most oscillators. I’m not so sure if the fundamental VCF will track 1/oct, but there are many filters that do this, but anyway what he’s doing at 1:50 is really sending a S&H to the frequency of the filter aka cutoff point. I hope it helps…
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