For people that will TL:DR what I’m about to say, skip to the last paragraph and just take my word that there is sustained reason for what I say there. Otherwise I will start my more in depth explanation of why with the assumptions, and reason for those assumptions, that where made to reach this conclusion.
First off I am basing this on the sets of standards for audio gear, so I its not applicable if they are using custom parts that do not align with these standards in any way, but seeing the simplistic nature of the plugs\cables anyway and the time\expense to do so I do not feel this is unreasonable to rule out.
I also assume they are not using the TinyTelephone standard (bantam plugs), which is possible, but I deem unlikely as this was a comparatively modern standard developed for patch panels and portable gear without the space for XLR, rather than the sorts of bulky gear being shown. They also use a 4.4mm connector, typically with minimally higher width of the entire plug, so normally look different than the cables in the video, however without seeing actual pins of the connector I can’t tell. Seeing as a standard for patch panels seems fiiting to the role I will also note that bantam plugs tended to be fairly poorly regarded by professionals of the time due to their limited power carrying ability, lower rated insertion cycles and decreased connection reliability vs the bigger 6.3mm plugs that where basically the only option in patch setups before the TinyTelephone standard was created.
Finally I assume there is no separate sub category for synth cables that I have not heard of as I cannot see the need for one, and after a quick poke around the internet I can find no mention of such a thing. But with this list of assumptions noted,then I will proceed by stating that they are using standard 1/4" TS cables.
These cables where originally designed for telephone exchanges, and are one of the oldest sorts of connector still in use today. They operate on a very simple naming system, firstly the size of 6.35 mm 3.5mm or 2.5mm which is the diameter of the plug, followed by a code that describes the conductors (T=tip, R=ring, S=sleeve).
From the video they appear to by using the screw together type of older style plugs, which where only common in TS, although there where definitely molded version made in TRS that came about slightly later as stereo headphone became a thing. TS cables by definition carry an unbalanced mono signal, and doesn’t provide a contact to allow grounding of external shielding. TRS cables generally carry unbalanced stereo, but some mix desks have used them in “balanced” (actully just differential signalling rather than truly balanced) mode as a slightly smaller alternative to XLR buy using both Tip and Ring to carry the monaural signal, one the inverse of the other, while passing ground down the Sleeve. However this never became common as the Sleeve contacts last so it generally creates a large amount of noise on insertion, and if a TS cable was used instead of a TRS would either bridge the Regular and inverse signal amplifiers output, which early solid state gear didn’t like, especially with line level and other “loud” outputs. Worse, if the other end of the TRS cable carrying a balanced signal was put into a device with a TS socket then the Ring that carried the inverse signal would be left powered but unconnected, which while tolerated just fine by modern amps it typically destroys valve based gear. XLR cables never had these sorts of problems and could also provide cable locking, so even with the slight size disadvantage they continue to dominate the analog side of the pro audio environment even to this day.
So am I certain its Unshielded? No. But on the other hand not only is it highly likely, it would create just as many problems if it is in fact operating on one of the less common setups that actually allowed shielded balanced lines.