This has been a big challenge for me: trying to avoid strumming to the exact beat of the words. It's hard to avoid, but practice will help. You need a steady rhythm for strumming, which shouldn't exactly match the sound of the words. I don't play this song, but it looks like four beats on Em and two beats on that F#m13 chord. A simple way to do it is just play all downstrokes. After you get this sounding good, try mixing in an upstroke or two, for example during the chord changes.

Also, when they put the chord between two words, it can be confusing. For me, it is hard to change chords in the middle of a word. I usually change at the beginning of a word. From what I remember about this song, you should change chords on the word "horse."

Hope this helps,

DC