This is simply some further explanation on the YouTube video.
Basically stringing minor chords together will often sound soulful however you need to be aware of the key changes, especially if you are using minor chords which are only a step or half a step away.
The chord break downs are below.
Gb minor 9th – Gb, A, Dd, E, Ab – (same scale as A major)
Ab minor 9th – Ab, B, Eb, Gb. Bb – (same scale as B major)
Bb minor 9th – Bb, Db, F, Ab, C – (same scale as Db major)
Practice switching between the three keys. Hint if you need to know the major scale equivalent of the minor chords, I suggest you refer to what is called the “Circle of 5ths”. This shows the relationship between the minor and major chords and is an invaluable tool (see below the video)