This example focuses on creating an HTML widget that plays a video hosted on an external server. This keeps the size of your *.ibooks file down making for quicker downloads and avoiding becoming a burden to iPads already nearly filled to capacity with other books and media.
Try viewing this video in full screen to catch all of the details. Note that Firefox doesn't like MPEG-4 and will refuse to play this. Try any other modern web browser (Safari, Chrome, etc.).
Download the example book to an iPad to get an even better view of how this looks and feels in the hands of your audience.
Download iAd Producer (free developer registration required)