Watch the Left Hand Mutes in Motion online guitar lesson by Rich Maloof from Guitar 201: Breakthroughs
Now we're going to play a consistent rhythm pattern that incorporates left-hand mutes. Go through the chords slowly at first until you can make the changes at tempo (there are more chord changes in here but not a lot of shape changing). The right arm is swinging away, hitting every up and down stroke but muting some of them. Notice how much more feel and motion the rhythm has with the mutes than it would if we were just strumming it straight.