Hi @campfire , the lesson is 2 fold. First, it goes back to knowing the octaves between strings. For example, let’s start with a C note on the 1st fret B string. The next closest C note is on the A string 3rd fret. From there, the next one is on the G string 5th fret. Then, both E strings 8th fret. From there, we go to the D string 10th fret. And finally, we go back to the B string 13th fret and start the whole thing over again. Notice that we just spelled “CAGED” (substituting the letter C for the B string) while going from string to string through the C octave notes along the fretboard. This is an important concept, because by knowing it, you can move forward or backward along the fretboard (starting on any string, any fret) to find the same note by equating the word “CAGED” to the appropriate strings. Tony is doing the same thing with the open G chord (starting with the open G string) and showing the relationship to other G chords along the fretboard. So looking at the spelling of CAGED, the next letter (moving forward) is E. Meaning that the next G note root is on the E string and the G chord happens to be an E shaped barre chord with the root on the 3rd fret loE string. The next G note root is on the D string 5th fret and the resulting G chord is played out of a D shaped barre chord. The next G note root is on the B string 8th fret and the resulting G chord is played out of a C shaped barre chord (remember that I said to substitute the letter C for the B string). And finally, the next G note root will be on the A string 10th fret and played out of an A shaped barre chord. So, once again we’ve spelled the word “CAGED”, but we started with the letter G.
Just go back and watch the lesson again when you’re ready, perhaps it will make more sense at that time. Good luck on your journey.