I think you need an instructor to work with in person, because although many of us are seeing the same things in your stroke, it's going to be very hard for you to change your bad habits to good ones based on written descriptions.
Anyway, here goes nothing:
Your right shoulder is a big problem. If the arm is going to be in line with the shot, the shoulder has to be directly above the cue. Your shoulder is outside the cue, i.e. the cue is below your chest/neck. You can rotate your right shoulder backward and leftward to get it over the cue by moving your right hip, which will change the angle of your torso in relation to the shot. If you move your left foot left a little, and pull your hips away from the shot so that your torso is a little more sideways (not facing the shot so directly), that will pull your right shoulder back and left, and using your video camera, you should be able to find out when you've pulled it far enough that it's straight over the cue. You should be able to bend your neck to keep your head in the same position it was before, even as your torso moves out of the way.
So, once you right shoulder is above the cue, your right elbow needs to be directly above the cue. This is easy, just move your elbow back and forth, perhaps using a mirror or your camera to find out when it's in line. If your shoulder and elbow are in line with the cue, your upper arm is in line with the cue, and your lower arm will be hanging straight down from your elbow to the cue, perpendicular to the floor. This is the alignment you need to allow a perfect pendulum stroke.
Once aligned, you should have a VERY straight and effortless cueing motion by moving nothing but your elbow, using your elbow joint as a simple hinge. Depending on how your elbow joint is hinged, you may need to turn your lower arm to make the hinge line up for a straight motion. You can do this by turning your hand back and forth (facing the back of your knuckles toward the shot, or pulling them back in to line up with the cue) while stroking freely, and noting what amount of hand turn gives you a straight pendulum.
Once you've got your arm aligned and your elbow hinging straight, a pefrect stroke is just a bicep-contraction away. Pull the cue back, and release it forward, pulling your arm forward smoothly with your bicep but avoiding ANY other muscle tension. If you can translate what I've written here correctly into an actual stroke, you'll be astonished how effortless it is to stroke powerfully and accurately through the ball.
So that's the mechanics as well as I can describe them. You also have some bad habits that aren't really mechanics flaws, per se. You stroke very suddenly (jerky), but once you have a smooth pendulum and have eliminated extra muscle tension, that should go away. You lift up as soon as you've stroked through the ball, and you'd get much more consistent results if you froze at the end of your follow-through to get feedback, where you can see your ending position, which will tell you if you stroked straight, and you can concentrate on watching the CB contact the OB and where both balls go afterward. If you consider this feedback to be part of the stroke, your subconscious will learn much more from each shot you hit, and you'll improve faster. Also, I noticed you seem to lift your elbow on your final stroke. Don't do that. You'll frustrate yourself silly trying to get consistent results if your elbow keeps changing position at the last second like that.
Hope this was helpful. If I were you, I'd read what I just wrote, watch your video again with that in mind, and then get an instructor to help you learn to actually get yourself into the perfect alignment/stroke position I tried to describe.
-Andrew