Ok, I may have spotted the problem watching the video, at least part of the problem.
When you tighten the screw on the roll motor slider try this.
Lift the camera a bit to take all the camera weight of the roll axis slider so there will be no stress on the slider when you tighten the screw, it is possible that it does not fall 100% in place so you might still have 0.*** some degree lean on the arm.
This is not so un common when balancing gimbals.
Then do a bit more adjustment on the tilt axis again with the lens pointing upwards, it seams to be just a tiny bit off moving forwards when you take your hand of the camera, few small things adds up.
Also I can see that you do not have the extension arm on that axis witch is good, if you removed that extension your self then make sure those eight screws are fairly tighten, not over tighten them thought.
One thing when you are balancing each axis then keep all other axis locked, then when going to another axis lock the one you have finished and free the one you are going to be working on. it makes everything much easier.
Also as Kim pointed out, take your time, don´t do this in a hurry