Using a short animated picture movie, such as a Generated Image File, or .GIF can be a fun way to get a message across. It can also allow a short movie to be played on the forum post, without having to link to an off site. If a picture is worth a thousand words, than a GIF must be worth at least as many frames as it has times 1000.
A GIF is like a cartoon, using several still pictures that change enough to create what looks like a moving picture. GIFs can be made from movies you have, or might already exist online, and can usually be found by typing a search describing what you want to see, or a scene from a movie or television set programme. If it is less than 512 kb, and there is no extra "video", then you can insert it into your post the same way as any other image file. But odds are, you may not find exactly what you want in a file size under 512 kb. So what do you do?
I use an online website https://ezgif.com/ Select what tool you want to use from the bar, upload the GIF file, and start customizing it.
I mostly use it to customize the size of the file to make it fit, by using the RESIZE tool. Notice that the file I chose is 325kb, small enough to fit as is. But let's play with the PERCENTAGE tool and shrink it down to 50%. Click RESIZE IMAGE and see the new size. If it is below 512 kb, it is ready to post, unless you want other changes. If not, you may have to go to a smaller percentage. click on SAVE. You can also crop the edges or cut frames from the beginning or end of the animation to shorten it, in order to make the file small enough to fit here.
Now find your saved file from EZ GIF and post it like a picture.
Give it a try. It's easier to use than to read my directions. The site also has tools to add effects, change speed, reverse animation, lots of fun stuff.
If requested, I can try to post demonstrations of these tools. Show me what you got and have fun with it.