Before I read your question of if the clunk came from the CABs, I was impressed by the video that the clunk and the movement did not seem to be related. It looks as if you need new control arm busings. Since the clunk seems to be independent of the control reaching the end of the travel within the bushing, I was gonna say the ball joints are suspect. I can't tell what you are pushing and pulling on to get the clunk, but if you replace the lower control arms and the bushings, you would take care of the clunk and the movement all at the same time. The lower control arms are not difficult to replace. Lift the car and let the suspension hang freely, and you can get the lower control arm off with a couple of nuts being removed and a pickle-fork.
If you wanted to inspect the ball joints, then reproduce the clunk noises again, and look at where the steering knuckle mounts to the lower control arm. There should be absolutely no movement in the ball joint.