I had to learn more about it after that short clip and found an overview page which is fun to read if your browser can translate it: https://www.dentsubo.net/circle/spe256.html

The PowerPC folks are a special breed of dork. One time… they renamed a bunch of instructions. There were some very plausible motives given for changing how mnemonics worked. Mentioning flag names was boilerplate, abbreviating “ex-” words as X was too American, that sort of thing. So officially, there’s no particular reason the Enforce In-order Execution of Input / Output command is EIEIO.