I was rather disappointed to see that they were animated gifs. I would much rather see them in a format where you can run them with independent speeds and framerates.
I figure it would be better to represent the image as a bunch of shapes with changing position/rotation. In fact using these animations as a base It might not be too hard to automate the process to identify the shapes and the connections between them.
The custom player takes the class of the div container (http://www.animatedengines.com/img/tprop_fl.gif) "aeplayer aepframes_6" to determine the number of frames (6) and offsets the background-position vertically for each frame by the amount of the individual frame height which equals the div container height, thus appearing animated.
Given that the site has been around since the year 2000, assuming the images haven't changed, the tools widely available / understood at that were rather limited when compared with today.
I figure it would be better to represent the image as a bunch of shapes with changing position/rotation. In fact using these animations as a base It might not be too hard to automate the process to identify the shapes and the connections between them.