This is from the first grow I did, PF tek style but with a few updates. I did a couple monotub grows a year later that went great but I can't for the life of me find any pics.
The white pebbles are perlite and the cake is mostly rice bran meal and fine vermiculite, with a little coffee and gypsum.
I just skimmed that video and this guy is a boss. Those are definitely psilocybe cubensis he's growing but he doesn't actually say it haha. The way he said "supplement" at the start had me wondering but you can clearly see when he harvests.
This is pretty much exactly what I did on later grows. I used rye berries instead of millet and I didn't use agar. Just spores directly to the jars of hydrated grain. Agar is awesome but it's also an extra step for contamination especially without a flowhood and i was just using a still air box. It also seemed like a real pain doing agar work with the limited mobility and visibility of working in a still air box.
That video is great, I'd check out all the steps on shroomery to make sure you understand everything super thouroughly, and having expert feedback when some weird color shows up or something doesn't go as planned can give you some great peace of mind.
Lol grow the "albino penis envy" cubensis variety, it looks cool as hell and allegedly is denser than other cube varieties which is kind of interesting.