Storyline preload handling

SL seems to start preloading by loading the current slide's assets along with the ones before and after. Then it starts loading everything from the first slide to the last. 

My guess is your load indicator doesn't display because SL doesn't display the swf until its 100% loaded. 

Our preloader loads all assets from first to last slide. It tracks the loading and updates the progress bar (and an SL var) so the student can see what is happening. In addition since we are updating that SL var you can build some logic in to disable the Next button until X% is loaded. 

If you want to display progress for an individual SWF I would recommend you build two SWFs. One will be the "real" content the other is a "loader". The "loader" should be same display size as the content. It will perform a simple loadMovieClip to pull in the "real" content while showing progress. Put the "Loader" file on the SL slide. After publishing SL copy the real content into the proper folder to match the path you put in the loader swf.

Keep in mind that mileage will vary.  Caching files is very much dependent on the browser, OS, and user settings.