He sets up a mic outdoors above a speaker (same speaker behind him in the room where he's sitting. I wanna know what they are!)
They are DIY speakers he designed himself, if my eyes aren't playing tricks on me. DIY Perks is a great channel in my opinion. It's possible he isn't entirely spot on all the time, but in my opinion most of his designs are very thoughtful and the end product is typically very high quality for very little money. He does fairly elaborate designs, for example he made some very creative PC designs where the cooling solutions are essentially silent.
The speakers are featured in videos on his channel. They are a cast type speaker where he 3D printed molds and experimented with trying to make the most "dead" material for the case. I'm sure they're easy to find on his channel, they're fairly recent videos. There are two or three videos on them I think, and while they're probably not entirely on par with the most expensive speakers, his goal was to create a very cheap speaker that could trade punches with much more expensive and established brands. He does post some audio and measurement comparisons to a 1200$-ish speaker.
While I wouldn't build these myself, the value seems excellent and it's generally just refreshing to see some more thoughtful content.
