Um, it took like an hour to learn how to do it.
Download the YouTube video as an FLV (lots of tools for this), convert the FLV to an MOV (I used WinFF), open MOV (or subsection of MOV, most likely) in Photoshop. You now have a looping animation from the YouTube video.
http://www.howtogeek.com/55949/how-to-make-a-youtube-video-into-an-animated-gif/Here's the tutorial I used to add text:
http://icon-tutorial.livejournal.com/11129542.htmlThe MOST IMPORTANT THING, which he stresses but I'll stress once more, is ONLY MAKE CHANGES WHEN THE FIRST FRAME IS SELECTED. If you move the text while a different frame is selected it will move it ONLY for that frame. What I did was position the text while the first frame was selected, then selected frame blocks to turn off/on visibility.
Animating text is fairly straightforward, just move it frame-by-frame - the harder part is NOT animating text and making sure it stays in exactly the same place for the whole GIF.