Right, power chords, absolutely. So when Ola mistakenly says "E minor" chord at Step 1 instead of "E5", I knew that it would cause confusion for the two Anderton guys. You hear them ask for clarification about 5 minutes into the video and Ola's like "oh, no, just the low E". Which still isn't a 100& accurate statement, but I give Ola a pass since English is not his 1st language.
The correct statement from the get-go would have been "you chug on low E only, and only hit other strings when you're stabbing at power chords occasionally for pauses/breaks in that chug rhythm, like E5 or F5, G5, etc".
I think an ideal song to practice along to for "My First Chug Song" - both stylistically and because the tab is readily available for free on the internet - is "Am I Evil?" as covered by Metallica.
I was about to say, let's go back in time to the beginning and listen to Judas Priest. Add Iron Maiden to that list as well. No drop tuning, just an abundance of chug.