I looked at the fretboard and was really confused where to begin....
1) Short answer:
He always starts from
whatever shape is lowest on the fretboard for a given chord and goes up and back.
So when doing G, you start from the lowest shape, which is the open G chord.
2) Further, longer, more drawn out explanation (from the video):
Before he goes into the Circle of 5ths exercise he goes through the C chords.
The lowest shape is the open C shape, then the A, G, E, D, C shapes up the fretboard and back.
Then he does F, specifically to point out that the C shape of F is higher on the neck. So he works his way backwards to get to the lowest shape. The lowest shape is the E shape, then D, C, A, G, E shapes up and back.
The order they connect is always the same, just starting from a different lowest shape. (Kinda like relative scales.
)
Then he does B. The lowest shape is the A shape, then G, E, D, C, A up and back.
When doing the Circle exercise, G then starts from its lowest shape, which is the open G shape.
(Left-facing from the 6th string root, if you prefer.)
Then the E , D, C, A, G shapes of the G chord up and back.
Then following the Circle you start D with the open D shape.
Then A from the open A shape.
Then E from the open E shape.
Then B from the A shape.
Then F# from the E shape.
etc.
Start from whatever shape is the lowest on the neck for a given chord and work your way up the neck and back.
3) My thoughts, not from the video:
If you prefer, you can think of the G shape as Left-facing from the 6th string root.
The E shape as Right-facing from the 6th string root.
The D shape as Right-facing from the 4th string root.
The C shape as Left-facing from the 5th string root.
The A shape as Right-facing from the 5th string root.
This will help when you want to get to a particular shape without having to go through all the of them in order from the C shape to get there.
This is similar to our pentatonic boxes. For example, knowing how to start from Box 3 without having to start on Box 1 and going through Box 2 to get there. And knowing how to play a scale to the left or right from a given root note in a box. In fact, these 5 chord shapes and 5 Boxes are related, occupy the same 5 areas of the fretboard and are connected by the same root notes.