Gif/Jif? However you want to pronounce it, gif files have made a strong resurgence in the past years, and they can be very funny. But gif can also be very serious.
In my work on Umbraco pull requests, the very best thing you can do to help me is to show me how things work, preferably a before/after is very helpful.
Until a few years ago it was not possible to post videos to GitHub, but images (including animated gifs) would work, so at the time the best way to post a video would be as a gif.