Building Preloaders and Progress Bars in Macromedia Flash
http://www.macromedia.com/devnet/mx/flash/articles/preloader.html

Hirsch, Joshua
Adobe
2005

Abstract:

One of the unique features of web content built with Macromedia Flash is the ability to control when and how the content loads. When loading a heavy HTML page, the user is usually stuck looking at a blank window until the content starts appearing. Flash allows for the creation of animated preloaders, which give the user precise information about the progress of the loading process. A simple rectangular progress bar or percentage indicator will do the job, but why stop there? A preloader should be given just as much love and consideration as the rest of the site content, especially on a site that is trying to evoke a mood, or create an immersive experience. If a preloader is engaging enough, the user won't mind waiting for content, and the time it takes to load will seem shorter. The preloader is the first element someone will see when visiting your site. You can make a good first impression by welcoming your visitors with a snappy preloader.