Since you mentioned that you were in 2" deep rough, it's worth emphasizing that movement can be downward as well as laterally. If the ball "settled" as a result of your placing the club behind the ball, it also moved....
The people who demonstrate using this are showing the true swinging action which imo is the essence of golf. Love the perpetual motion drill.
All these devices are based on the same concept. That should tell anyone who is a student of the game something important.
swing the clubhead!