How do you DO that?

The small repeating videos are called gifs, which is the type of file that they are (the extention is .gif) you can make one on this site http://www.createagif.net or you can look them up on google.

......

Take out the URL part and change the IMG to all lowercase letters. Should look like what I show if you did it right.

Can't use capital letters. Should be [ img ]http://cdn.makeagif.com/media/8-09-2013/ifSHtZ.gif[ /img ] without the spaces.

Any address you copy should have .gif on the end for it to work.
http://i56.tinypic.com/169knzo.gif becomes:

quote this post and look at the text that you are quoting.

http://www.myfitnesspal.com/topics/show/145822-when-you-post-pictures-on-the-forum

youtube is NOT a gif. For gifs you can search google for gifs. So lets assume I looked up cat gifs and found this link http://i.imgur.com/J6BgPuK.gif

You can tell its a gif because it ends in .gif

after finding the link, surround the url (that would be http://i.imgur.com/J6BgPuK.gif) with [ img] and [ /img] (except remove the space between [ and img])

You have