That's absolutely gross and it's possible an expert can clean it and have it good as new, but, man, that's disgusting.
I'd not even hold the controller or buy for $5 if he wanted.
Well that what you call a mini civilization there, well who ever buy it prepare glove, air gun etc.
And ear plugs, nose plugs, mouth plug and butt plug if necessary

I've disinfected and restored some disgusting old hardware with an extensive process I developed using isopropyl alcohol, white vinegar and distilled water. It's not for the squeamish, but sadly some older systems are just going to end up in a bug infested house at some point and end up with what I assume is in the video (I'm not watching that). It's a nightmarish process but it can be done.
It's not a bad idea to either open and inspect second-hand electronics immediately, or else seal them in a bag for a few months just to be safe. Better still if you pour some diatomaceous earth into the bag before sealing it, as it kills insects.
I have sorted worse. Granted it was £3000 for a fixer upper on ebay gear with downtime costing notable amounts as well.
Would I do that for someone? Probably not, or at least it would be one of those beyond economical repair.
Would I do that for me? I am an exceptionally cheap bastard so I would give it a swim in some chemicals or allow it to freeze for a while (possibly with some canned air) to get a controller.
That said I can see why some would opt for the opening of my favourite 60s song
Also curious what the creepies are. Most times plastics don't get that sort of thing so I would wonder if it is one of those pumped up for clicks things
Seen similar in books before though so maybe.
This handgun vid made me distrust a lot of more mainstream handgun restoration videos(where they magnet fish it out of the rivers n stuff. I've found a Smith and Wesson( https://gritrsports.com/smith-wesson/ like of one of those ) revolver myself and it looks nothing like those fake rust ones.