I heard animated gifs can be even larger than movies because each new gif frame loads an entirely new image whereas video codecs will only change pixels in a frame that are different from the previous frame’s pixels. It’s probably more complicated than that but some gifs can reduced to a 48:1 ratio using programs like gfycat:
However, it never really caught on because people seemed to wanted to use the browser non cross platform compatible plugin called Flash instead of a format that could been built into every browser for any platofrm. LOL. Oh well.
The other reason it may not have caught on was that there were very few (good) programs to create the animations themselves by comparison to the other competing formats.
Google’s WebP should be a good choice - google it. As of now, only chrome browser supports it. Also, the format uses the same algorithm used by google’s v9 codec.