Most animated gifs on the referenced page work, one doesn't. The one with problems in Mozilla 0.9.1 works fine on Netscape 4.77 on Linux and IE on Windoze.
*** Bug 84811 has been marked as a duplicate of this bug. ***
Dup. The animation that doesn't display is really 480x480 pixels, but is resized to 380x380 on the page. *** This bug has been marked as a duplicate of 74313 ***