This is more a breakdown than a full detail tutorial. I want to give you an idea how you can animate a rigged character
in After Effects with BeatEdit for After Effects. The bassist character we use here has been created by Tobias Hart aka 2biasMotion
In this tutorial you learn how repeat any animation in After Effects easily at each marker. You first keyframe the animation and then you apply an expression that plays back those keyframes at each marker.
In this tutorial you learn how to create symmetric shapes with a super useful expression.
The Mirror iExpression can mirror any shape for you and you can even get an instant preview of the mirrored shape while you are modifying it.