A GIF plays everywhere without a Play button: in email, in a GitHub README, in chat and on forums. Add a video above, pick the width, frame rate and length, and the converter builds a palette for your clip so colors don't band.
GIF is a heavy format: at large widths each second costs megabytes. So the GIF takes the start of the clip, 15 seconds by default and 60 at most. For chat, 480 px at 10–12 fps is usually plenty.
If the platform accepts video, MP4 is both lighter and better looking than a GIF. Going the other way, GIF to MP4, works here too.