In large parts, the patch field of the MS-20 offers control voltage possibilities that the majority of synthesizers offer ready to use via knobs and switches, like…
…allowing the wheel to control the pitch, or
…using the button to engage LFO vibrato, or
…creating random staircase LFO waveforms.
The audio path is in fact non-modular: all you can do is to inject an audio signal, you can’t break the VCOs-Mixer-HPF-LPF-VCA chain.
I could go so far to claim that the patch field of the MS-20 mostly has an educational value, as it helped me to understand and use the basic principles of voltage control.
So the comparatively minimal patching in the video is – from my perspective – a consequence of the comparatively limited patching capabilities.
The exception being the MS-20’s External Signal Processor, which can not only serve as a audio-to-CV processor (I fondly remember using my Casio VL-Tone’s sequencer to control my MS-20), but which offers a non-voltage-controllable HPF-LPF filter with lots of gain distortion, which can really help shaping e.g. the MS-20 phone output when it is used as a feedback or modulation signal…
…which helps creating (at least in my ears) the most organic, acoustic-instrument-behavior-like sounds in the MS-20.
Disclaimer: I love my MS-20. It was the first analogue synthesizer I got, back in 1982 (the first synthesizer was a Casio VL-Tone VL-1 in 1981). I sold the MS-20 in 1985, because I thought I knew it (haha!), bought another one in 1989 (together with an MS-50 and SQ-10), traded all three for an Oberheim Matrix-6R (fail), bought another one in 1994, but thought this was a sentimental move, so I sold it in 1995, only to regret it and bought the final one in 1997, which I kept.