This video, via perfectcircuitaudio, captures a demo of the vintage Oberheim Two Voice analog synthesizer.
The Oberheim Two Voice, from 1975, combined two Synthesizer Expander Modules with a 37-note keyboard to create, what was then, a compact polyphonic keyboard design.
Designer Tom Oberheim has recently updated several of his classic designs, including the Oberheim Two Voice synthesizer. You can get info on the updated versions at his site.
Awesome video! Definitely captured some cool stuff, but I think it may have short-changed the unique character of the variable filter, i.e. putting the knob somewhere between a lowpass and a notch filter with modulation makes for some preposterous sounds whether in monophony or polyphony (we got a bit of a taste at 2:14 onward on the sequencer, but the attack/decay used prevented us from hearing much of its depth outside of the resonant frequencies).