Stop-Work Relativity Winding
The animations below show the mainspring being wound from the three different perspectives. The most useful perspective is that of God and the Barrel.
Winding relative to God; this is the normal, external view of the watch.
During winding the barrel arbor is turned anti-clockwise to wind the mainspring and the barrel wheel limits the number of turns. Because the barrel does not rotate, this is also the view from the barrel.
Winding relative to the arbor wheel.
In this view the arbor wheel does not move and its pin always faces right. During winding the barrel appears to rotate clockwise. Looking at the winding relative to God above, the arbor wheel pin rotates. If you imagine, at each step of that animation, you can rotate the barrel to keep the arbor pin facing right, then you have to rotate the barrel clockwise and you have this animation.
Winding relative to the barrel wheel.
The barrel now appears to rotate anti-clockwise intermittently. Again considering the winding relative to God above, the barrel wheel stays in the same relative place, but it rotates. As we want this wheel to be stationary, we have to rotate the barrel and arbor wheel around the center of the barrel wheel to keep its orientation the same.