That's interesting, considering there's a whole new trend of websites dedicated to converting heavy GIF files into small video files instead - sites such as https://gfycat.com/about
When gifs started breaking the promise of being fast to load, due to people sharing fairly large res animations, sites such as gfycat tried to replicate the promise of silent sketches, but with more modern technology.
This is not bizare at all. Less is sometimes more.
I can't help but feel these tools are evolving in the wrong direction. And not even in a "Stop liking what I don't like!" kind of way; simply that the solution could have been reached with far fewer steps.
Remember Windows 95 played AVI videos e.g. in the file copying dialog. The AVI video consisted as a series of BMP pictures. All magenta colored areas where interpreted as transparent. (info about the special bitmap based AVI format: http://www.endurasoft.com/techtalk/AVI.aspx ) A 486 66 MHz with 4MB memory could play that short small videos. The Win95 CD contained two movie trailers afaik with an early Intel video codec, it took a more powerful Pentium 1 CPU to play them at 320x200 (Intel Indeo codec: https://en.wikipedia.org/wiki/Indeo ).
Coming back to GIFs and MP4/HTML5 videos. GIF is an old format from ca 1989, showing them is less CPU intensive than playing MP4 videos. Firefox on PC and all mobile browsers on iPad and Android that I tried had serious performance issues with 100+ very small videos. Interesting that GIFs mobile devices with even just 512MB memory can show at least 100 GIF videos (each 5-15 MB filesize) on one page.
It seems like something that would be quite possible, with a number of applications, but don't know offhand of any tools like that.