Watch the Flying V online guitar lesson by Brad Carlton from Chord Studies: CAGED Chords Vol. 2
This progression is a V - IV - I in the key of A. The first chord is E utilizing the A form out of the CAGED system, and then we switch to a D chord with the G form. When playing this chord, barre all six strings, as it will help you to keep your fingers upright. Your fingers can get a little crowded on the A chord with D form, but your second and third fingers should make somewhat of a "V" shape to facilitate the form.