I disagree with most in that the footwork is the major culprit. Of course, a player could work the remainder of their life on improving their efficiency of movement. However, in two of the more critical aspects, alignment and redirection of momemtum,,,,you do a resonably good job with.
One of the more pressing problems is (and this maybe more conceptual) is your desire to lunge at the ball. Understand, you will not hit the ball any harder, or maximize spin momentum, when you lunge in the direction of your weight shift. In this case, (with an open stance) the weight shift is more lateral in nature. Can you see how, (on almost every ball) you tilt your spine in that direction? Can you see how that throws you off balance when you create dynamic rotation of the core? One of the basic tenents of rotational efficiency is what I call vertical stacking, which is simply shoulder over hip alignment i.e.Good posture......This will tremendously improve your balance, increase spin momentum, lead to better contact/swing path integrity, and speed up your recovery loops.
Also, as some have mentioned, the use of your left arm, is way off. As you take your final step out to the ball, (right foot) get that left arm straight, and across (parallel) to the baseline. Sweep it across, (in the direction of core rotation) and then tuck it....This movement increases angular momentum...Gone will be the days of your arms crossing...a big no no.