I did some searching for you and didn't find anything on YouTube. I did read somewhere in a 2009 thread that all Betty Cotton's demos can be watched on Nancy Zieman's website. But when I went there I didn't find them. Maybe they have been taken off since then.
But I did find two videos of Nancy doing this on a foreign You Tube. Here's how I got there:
On Bing I searched "Cotton Theory video" and in some boxes of pictures that appeared there's one of Nancy Zieman, "You Tube: Learn how to use your Cotton Theory quilting". Click on that picture, then double click the video that comes up. Then you'll see that video on the foreign YouTube.
In the list of videos on the right, you'll also see one of Nancy Zieman titled, "YouTube-Learn the original quilt first then". I was able to click on that one, too, and view it. But I wasn't able to get sound on either video, maybe you can do better. Good luck. Hope this helps.