Timethief...I had a look at your link but that's not what I've done. Mine is just an animated gif so doesn't require any script or PHP fiddling.
My gif is made up of three pics...60 seconds for each photo, then 5 pics 20th of a second long using varying amounts of transparency to merge to the next pic. Definitely an animated gif...I could just as easily create a stick man running across the page.
I assume the method you refer to would create a much smaller file, but I believe I'd have to pay to get customisation etc to get it to work? Plus I haven't a clue where to start with PHP etc!