Here's a simple drag-and-drop flash preloader movie clip.
This FLA file contains a movie clip called Preloader. You can use this clip as a drag-and-drop preloader for all of your swf files. Style the preloader clip to your liking. Percentage loaded bar and text status bar are included and may be removed easily.
In frame one of the movie you want to preload, place the Preloader clip in its own frame. Preloader will stop the main stage movie until it is loaded completely. Once loaded, the Preloader will hide itself and play the next frame in your main stage. This sample waits for a sound event to preload before moving to the next frame. Once there, the sound clip begins playing.