Seems like a lot of companies are willing to sponsor the “major YouTubers” because they increase the sales through publicity of the devices. I’m sure when they first started before becoming popular they put a lot of stuff on credit. I’d bet they still purchase some things on credit, while being provided free rental units for reviews and videos. After this long, Cuckoo probably owns most of the main gear out, namely the ones you see repeated in videos over a longer period of time.
I’ve heard better music from most Elektronauts ironically, as opposed to the core synth YouTubers. I like Cuckoo though. That video looks like it’s on some Moog property/at Moogfest though due to the amount of plants.
The YouTube synth community is a strange one. There’s a video of Noir Et Blanc mentioning it’s likely not worth it.