Here’s what Randall has to say about it:
The Analog Four is sequencing the Oberheim SEM via its first CV outputs, and is sending a clock track and a trigger sequence to the Eurorack via its second set of CV outputs. In this way, I can control three separate sounds in addition to the four available in the A4 itself. The SEM and Eurorack audio outputs are going back in to the A4 via its audio inputs, and then the A4’s stereo outputs are recorded in the camera.
No DAW, no MIDI, no plug-ins, no computer at all.