It's because those GIFs are MP4s coded with high levels (6.0 etc.) that normal hardware can't play.
Disable "Hardware-accelerated video" decode in
(type this is address bar)
Keep "normal" hardware acceleration on!
Chrome > Settings > Advanced > System > Use hardware acceleration when
Facebook allows posting animated gifs but stops them from actually being animated programmatically. There are a few apps out there that claim to let you animate your profile, but anyone visiting would need to have that app installed as well to see it.
you can't upload swfs to Facebook, and videos won't autoplay.
I do have to admit, you gave a lot of ...
Facebook doesn't support neither animated GIFs nor video files. Moreover, no self-respecting web service with user-generated content will ever allow SWF files because they're not multimedia but rather executables (i.e. applications) and pose incredible security risk.