Breguet: Watch No. 28 Self-Winding Stop-Work
The following animations repeat indefinitely, but they cannot be reset. I suggest you use Firefox and install the following extension (or similar if others exist):
Firefox addon to toggle animated gifs
The two animations below show the mainspring being unwound and wound from the perspective of the barrel.
If the annulus is smaller then the mainspring will wind an extra turn. The following animation shows this, starting at the end point of the above winding animation.
Winding Small Annulus