I succeeded to upload finally: You can see how the bubble moves during the shots around. But the only shots you have to level are the first one, and the Nadir2 shot, after having moved the tripod aside.
Heinz, That's a very large file for such a short video. What is it intended to demonstrate? We all know that the bubble moves around on our own panoheads. If you get the bubble exactly in the middle for the first shot, it doesn't guarantee that the camera is exactly level for that shot, does it?
Heinz. For a newbie, then, it's not enough to say "But the only shots you have to level are the first one and the nadir2 shot". The user is entitled to assume that the other shots can also be levelled to be on the safe side, though maybe not strictly necessary. You need to add something like "You must not re-level the head for the other shots."
I leveled my m2, but instead of look down at the bubble I look at from 90 degrees and 0 degrees using the sides of the bubble circle as the boundaries. When I do this and check my level as I rotate it remains within the boundaries of the bubble circle. There is a way to wash out level error, as we used to do that as calibrator in the Marines. It is meant to reduce the error, not eliminate it though.