This tune is from the Core Skills section on Harmonics.

Harmonics can be used to great effect with acoustic music too. Here we play through a fast but simple chord progression:

E major - D major - A major

As we change between chords, notice that the open strings are quickly strummed. This achieves 2 things. Firstly, it makes the chord changes smoother, because it gives the fingers time to change position as the open strings are strummed. This means there is no break in flow and your fingers have time to reach their next destination. Secondly, it helps set up the harmonic strikes (here and here).

How so? Well the answer is that the harmonic strums all involve playing notes that are strongly related to the open strings. They are all natural harmonics.

This is part of the reason that these particular harmonics chord strikes are very common in acoustic music. They won't work so well with all chords, but for many open chords you can use them in this way. They give a pleasant break in the rhythm and offer you more variety in your arsenal of guitar tricks!

One last thing - Notice that the 2nd finger is used to play the harmonic strikes. This is because it is commonly the longest finger, so naturally can reach across all the strings more easily than the 4th finger, which may be slightly closer to the 12th fret, but is shorter. You can use any finger you wish, but the 2nd is often considered the most practical due to its length.