I'm no pro so you may want others to advise. I just noted that in the video you are doing stop shots and wondered if maybe giving it some top and then you could see how well the cue ball follows in line. I think if your stroke is not quite right and you try to follow with the cueball ( don't worry about scratching) It becomes more obvious on a stopshot you are basically skidding the cueball across the table up to the object ball.. . I know you may want to do that in play sometimes for obvious reasons.
My suggestion is to try the very same shot only higher on the cueball and then watch, see how close you can get the cueball to follow rather than worrying about only the accuracy of the pocket.
although that is normally a "bad shot resulting in a scratch" It will also show how well you are able to keep the cueball tracking in the same trajectory.
I think your immediate inclination is to stop the cueball so that you do not scratch, but maybe try to put the cueball right on the pocket ledge just before it falls in. and that might help work on the weight ( speed) as well. you can experimant by trying to drive the cueball a specific distance past the point of contact.
I find when I try to do the reverse and draw the cue ball , it reduces my accuracy and some of that may be just a skill i need to work on more. Many times I try to create a draw and it results in more of a stopshot. I know it has lots to do with how low I'm hitting the Cueball and the follow through. I play more snooker where this is obvioulsly important but it is basically the same in other games I would think. You are still positioning with the next ball in mind.
part of it is definitley inthe ergonomics and arm movement, trying not to bump your body etc. part is about NOT applying spin.
My theory is that it's possible to be in the habit of hitting a tad to the right or left of center and compensating for that in your aim.
I think when you draw your attention to trying to make the cueball follow in line wiht the OB , then any spin will throw that off. Sure you do want to use spin on many shots, but maybe you also want to be able to NOT apply any spin.
I think it's easier to see that with the cueball following the OB, because if you hit the CB a tad off-center, althought he shot may be in line with the pocket, the two balls won't "chase each other". Instead they will both have a different trajectory.
It is not so easy as you first think to keep the CB on the same line as the OB. If you can do that consistently I think it also says that you are getting your stroke closer to being straight and true.
You might see what others comment about that. Those with more experience might chime in with other ideas.
It's not my objective to throw you off with my somewhat inexperienced comments, nor to try to come off as a knowitall.. I'm learning too.
in the above shots showing stance and a few shots. also note where the "stopped" cueball goes. To me it looks like the CB is jumping over to the right hand side. Im not saying it was a "bad shot" but my point was ust that if the shot really was perfectly aligned the CB would not go to the right or left of the path of the balls trajectory. The energy to make it jump over by an inch or so to the right, upon impact, is coming from somewhere and of course it's not abnormal.. It is never a perfect world.