The main criteria was their audience similarity on youtube (youtube recommendations), as I told you in the first reply. I took the obvious pro-Kremlin channels and then pulled all of their top recommendations until I stopped finding new channels. Almost all of the top recommended channels were the ones you see in the graph, most of what I removed were various music/movies/etc channels.

There's a similar network of obvious pro-Ukrainian propaganda out there on youtube as well, and a large anti-Kremlin russian opposition network, they are all fuzzy but you can still see the clusters as similar channels have similar audiences and get cross-recommended by youtube.