Check out this site-archived SB2—lots of explanations of various numbers and cults. I’d start with the first couple of ones at the bottom though to get the basics of what he’s doing.
I’ve watched most of Serial Brain’s videos.
His research is impressive.
Most of the time, his numbers calculations, conclusions & inferences seem like so much mumbo/jumbo to me—though his conclusions seem somehow fitting, most of the time.
Sometimes I fast forward to the conclusions. LOL.