This free Irish guitar lesson from Folk Friend covers the “chord scales” for G and D ionian. These are super easy chord shapes for backing guitarists, which fit with Irish and Celtic tunes in these keys and can easily be played together at speeds. They also create nice runs of linking chords and will work in the other modes related to D major and G major; A dorian, D mixolydian and E aeolian for G and E dorian, A mixolydian and B aeolian for D.
You can learn more about the modes with an Amazing Mode Wheel, in my first book, Backing Guitar Techniques For Traditional Celtic Music, or on my free blog here.
There are two other videos in this series, dealing with: