[derefr]

I've saved the .webm of a converted "gifv" video on Imgur before, then reposted it to Tumblr. Works just fine—but the result doesn't quite get the same controls a Tumblr-converted gif does.

Really, sites just need to have a way to differentiate these types of video uploads and treat them with looping-animation UX, rather than video UX.

An easy solution would be to come up with an alternate extension for saving these videos, that other sites can recognize. This would be similar to, for example, the way iTunes knows to treat an MP4 container as an audiobook if it's an .m4b, or as a ringtone if it's an .m4r.

Another solution (and better, in my opinion) would be an extra wrapper/container document format around a video file, prepending at least a new extra magic number to allow mime-type differentiation via libmagic. I'm honestly surprised that "gifv" isn't already such a container-wrapper document format. Note that such a format doesn't need to be recognizable as a video on your computer (although support probably would be added soon enough); it just needs to be able to be reuploaded to other websites. (You could also add an extra chunk to e.g. an MKV container that, when present, would change its detected mime type—but this would restrict gifvs to only ever being MKVs. Might not be a bad thing to standardize on a video container format.)

Of course, the solution that requires no community buy-in is to just come up with a way to heuristically detect "silent short video file" on upload, and treat anything that fits those criteria as an animation rather than a video.