The document provides a tutorial for preloading external JPEG images or SWF files in Flash. It demonstrates how to use the Loader component and progress bar component to preload a 550x400 JPEG photo of the Tasman Sea in New Zealand from an external URL. The tutorial outlines setting up the Flash document size and publish settings to match the photo, adding the progress bar and loader components to stages, and providing the necessary ActionScript code to load the external image and track loading progress.