I watched your video AFTER measuring the smaller pond, and realized I might have the wrong pond. The drain-inlet in the above aerial images didn't match the orientation of the drainage-inlet shown in your video.
The below images should be correct, since the drainage-inlet in this larger pond matches the position shown in your video. The image below taken in '08 was much sharper than the '10 image; plus the lack of tree-foilage in late April'08 allowed much better definition of the pond's perimeter.
