Technically a chord needs three tones. What Jake is showing in the video are dyads made from root tone and its fifth.
A true power chord doubles the root tone thus giving it three tones and technically making it a chord. How is this so?
Well if you remember from Intervals, the Fretboard and the Strings, the interval between a lower string and a higher string is a perfect fourth, except between the G and the B, which is a major third. An inverted perfect fourth is a perfect fifth.
So you will find the fifth of a root down one string toward the floor. Thus to play power chord, you fret a string with your index finger, fret the next lower string, two frets to the right and fret the next lower string right above the same fret.
What Jake plays throughout the video are dyads. A dyad is two tones that can imply a chord.
All the same, Jake's lesson is stellar. He is one of the best "learn rock guitar quickly" teacher on YouTube.
