Matt Heaton - Mixolydian Modes

Mixolydian Mode is a major mode, the first chord is Major. Mixolydian modes differ from Major modes in one note.

D major scale: D, E, F#,G,A,B,C#
D mix scale: D,E,F#,G,A,B,C    = Mix mode has a flat 7 - it is a G-Major scale starting on D!

A major scale: A,B,C#,D,E,F#,G#
A mix scale: A,B,C#,D,E,F#,G = D-Major scale starting on A!

Here is the chord chart with the chords Matt mentions in his video. Don't worry about the chords names, they are generated automatically by the app I use. By the way, the app is called GuitarToolkit and is really recommended to every guitar player. It is also very useful for mandolin, bouzouki, banjo etc players!

Generally speaking: in A mix you can use the chords you would use in D-Major,
in D mix you can use the chords of G-Major, in G mix you can use the chords of C-Major.