Maybe it is just an arbitrarily long time in the past, since there were no computers then there is no history related to branch prediction so it's a joke that makes it sound like a longer spanning history than it actually is.
the BC made no sense to me and there's no reference to it.
If he made an illustration about hunters tracking their prey and there was a fork in the road and they split into 2 groups that could allude to branch prediction, I don't know
You might be interested in this note by Oleg Kiselyov which talks about branch prediction in the context of one of the 1st computers: http://okmij.org/ftp/Computation/Zuse-accolades.txt
Another beginner-friendly explanation of the effects of branch prediction is this Stack Overflow post which compares a processor to a train: https://stackoverflow.com/questions/11227809/why-is-it-faste...