Why putting two hot GPUs in a closed case? And for 1 grand you should be able to squeeze inside a standard rig a lot more used rx 580 (at least 6 for 600-700 USD)
I think the target audience here (Noob/Beginner) is someone that wants a dual purpose rig that can also mine. I like videos like this as it shows all the in/out of everything and now when people ask this question of "how can I get into mining?" instead of me having a 30 minute conversation with them, I can just link them this video and tell them to watch it.
Since most noob/beginners aren't going to risk buying used cards, I would expect they would be looking to buy something new on a budget.
Regarding heat, I agree the case choice here is less than ideal but you could just leave the side panel off and negate a significant portion of the heat problem.
My criticism on this video; it skips over the entire portion of what hardware was selected, why it was selected, and the costs associated with it. Although the list of hardware can be found in the blog post, a noob/beginner isn't going to know why they are buying the pieces they are buying and I think it would have been better to have this information be spoken to in the video so noob/beginners can better understand why the hardware was selected.
That being said, still gave it a thumb up.