The instructions tell you to “copy the URL that appears at the bottom” after you have uploaded your image. Since PhotoZoom has changed to DeepZoomPix, these instructions no longer apply (there is no URL at the bottom of the image in DeepZoomPix).
Until they update the documentation, you can use fiddler to discover the appropriate url for your DeepZoom image.
After adding your image to a DeepZoomPix album, launch Fiddler and browse to your album. Fiddler should capture a series of requests that looks something like this:
The url you are interested will point to an xml file and will start with something similar to /DZ/100/0/Image/ (look for that Image directory). Right click and copy the URL.
Then, navigate back to the Live Labs Seadragon Wizard, and paste the url into the appropriate textbox (shown below) and you should be good to go.
Here is the final product:
Hope this helps,