Ah, it also seems that not all browsers fully support this type of image - Internet Explorer, Safari, and Chrome will only display a preview image. It should work properly in Firefox, SeaMonkey, or Opera.
Is there a way to view them outside of using one of the mentioned web browsers?
There's a list of programs that support the format at http://en.wikipedia.org/wiki/APNG, along with some of the technical details of the format. There is support for the format in a few stand-alone image browsers - the best one I've found so far is XnView - http://en.wikipedia.org/wiki/XnView - which is freeware and seems to be pretty decent overall so far.
For those interested, post #749623 is another animation that I put together from this very same scene. If I find any other worthwhile scenes in the game, I'll see if I can do the same for those as well. (I'm particularly wondering if post #407616 is from an animated scene...)