My guess is Youtube took the channel down if they knew about it...can't be getting that bad press now can we?
I don't think it can be ruled out as a possibility, either that the video games they played were a reflection of their long-standing interest in this topic, or that these video games were an "inspiration" to them with the details of how they carried this whole thing out. JMO.
Also noticed on Bryer's Steam account it lists his location as "Atemar, Mordovia, Russian Federation." Now that is weirdly specific.
From Wikipedia:
Mordovia - Wikipedia
"The Republic of Mordovia is a federal subject of Russia (a republic)."
Saransk - Wikipedia
"The Russian fortress Atemar, founded in 1641, took its name from a nearby Mordvin village; at the time the fortress stood on the southeastern frontier of the Tsardom of Russia."
I guess that kind of answers our question to if either of these two read and what they might have been reading. Like...who just randomly knows about that kind of thing?