Preview
Templates include a small preview image of your running presentation. When you create a template, a snap shot image is taken at the point you clicked on the 'Export to separate template file' menu option. This screen then shows you that image.
If you have a presentation with a play list of pictures, video, RSS feeds, etc, then the presentation on screen will be constantly changing. So if you are not happy with this preview, then close this screen and select the 'Export to separate template file' menu option again at a point when the presentation on screen looks the way you want it to.