All this rigamarole is to trick the computer into doing substitution/elimination, which you do easily.
So what relevance is it to know this incomprehensible garbage?
If you are programming a computer to do it -- he's showing how the computer does it.
If the computer does it, why do we need to know? And I'm saying too -- I have no clue how I'd be able to explain the procedure to anyone, let alone a computer.
Programmers work w/ it and love it. He hates it.
You don't ever have to deal with this crap unless you are dealing with a programmer.
Programmers make more sense than this.
He's a teacher.
In short, it's magic and he learned the words by rote and he's mispronouncing half of them and the gods have been pleased to grant his plea anyway.
Rote learning = examples -- multiplication tables, certain definitions, anything you memorize and rattle off and then they ask "What the hell did you say?" and they rattle off the same thing again.
6x6 = 36
6x5 = 30
5x6 = 30
You know it, but it's just stored in your head and you have no real clue what it means.