Watch the Powerful Voices online guitar lesson by Brad Carlton from Chord Studies: Power Chords Vol. 1
This progression is using power chords with a three-voice structure. The first chord A5 is using a voicing we've done before and its root, fifth, root. Stay in your same position and go to G5, then switch down to fourth position for your E5. Then we bring on home by moving to fifth position for the D5 chord. You could strum these or hybrid pick these. Experiment with both to get a sound you really like!