When you hold your cursor over the buttons they grow tall to indicate the active image. If there are more image buttons than fit on your page, then the whole menu scrolls back and forth based on your mouse position. The image loads and determines whether it should base its height on the width or height ratio to make it fullscreen. While the next image is loading the current image gets dark and a preloader pops up. Hold your cursor over the caption and it will scroll upward so you can read the details. If there is no caption, there will be no caption button.
You don’t need Flash to be able to use this file. Everything you need to edit is in the xml.
You can customize the color of the buttons, text, maximum and minimum button height, button width, active button height, caption and caption colors. The entire file is just 11kb.