If you save an animated post from X or Twitter and end up with an .mp4 file, nothing is broken. X usually stores the animation as a short looping video instead of serving the original GIF.

Why X converts GIFs to video

GIF is an old format. It has limited color support and compresses animation inefficiently, so a GIF can be several times larger than a visually similar MP4. X transcodes uploaded GIFs into video to reduce bandwidth and make timelines load faster.

The interface still calls the result a “GIF,” but the media delivered by the CDN is commonly MP4. Renaming the file extension from .mp4 to .gif does not convert it; it only gives a video file the wrong name.

Choose the output for the job

Use GIF when you need a file that loops automatically in documentation, a chat app, or a tool that accepts only GIF uploads.

Use MP4 when image quality and file size matter.…