Originally Posted by: adam_henthorne... i understand the concept behind the dominant VII chords but i cant understand the flat 6th and 7th chords that he put into the progressions.

I think you are confusing two separate concepts: the numbering of chords in a progression and the numbering of scale note degrees.

They are related, but distinctly separate things.

Music Theory uses standard numbers to designate scale degrees.

C major scale:

C (1st, root) - D (2nd) - E (major 3rd) - F (4th) - G (5th) - A (major 6th) - B (major 7th)

C minor scale:

C (1st, root) - D (2nd) - E-flat (minor 3rd) - F (4th) - G (5th) - A-flat (minor 6th) - B-flat (minor 7th)

We then use those numbers to build and identify chords.

C major chord:

C (1st, root) - E (major 3rd) - G (5th)

C minor chord:

C (1st, root) - E-flat (minor 3rd) - G (5th)

C7 chord:

C (1st, root) - E (major 3rd) - G (5th) - B-flat (minor 7th)

And so on.

However, when we designate chords in a progression music theory uses Roman Numerals. We use the scale degrees as the source of labelling the chord (by it's distance from the root of the home key; the scale we are using). For example a chord progression in C major:

C major (I) - D minor (ii) - G major (V)

A chord progression in C minor:

C minor (i) - B-flat (flat VII) - A-flat (flat VI) - G (V)

Make sense?

I have a complete, concise overview of Music Theory here:

http://www.guitartricks.com/tutorial.php?input=495