In my newsletters, I often like to include short gif from movies so that they can play right in the email. To do that, I need to convert movies (e.g. from my phone) to a GIF file.
ffmpeg -i Untitled.mp4 -r 10 -s 480x270 output.gif
This requires installing ffmpeg
if you haven't already, of course.
Some times the file is either too large or too slow or feels choppy. In those cases I will use a GIF editor (even an online one like this one would work).