REMINDER:

This is how Loading external swf files into a main flash movie works: You build the basic interface for your project, with the content that is going to be needed to "beging rolling". You build other big scenes on the side: slide-shows, big Movie-clip symbols, high-resolution version of pictures, long sound-track sounds, and other media.
You build those on separate Flash documents (that produce separate swf files).

The "Main Interface swf file" (the mother file), will appear on the web embedded in a html document. Those 2 elements would be normally placed in a folder that goes straight ahead to the Server (Root folder).You will also place the swf files that will be loaded into the main one in THAT same folder.

The external swf (your Slide-show) does not carry the background color when it gets called inside a Main movie.
If the content excedes the Stage area (a big image zooming in, a text moving across the Stage from side to side)will be seen when loaded into a main swf.

THE EXTERNAL FILES:

In this page I am going to show you a simple way of placing all the external files together.
Your content for the different external movies might have already exist in separate Flash projects. In that case, you just put all the "fla" files together in a folder, export them to "swf" format one by one, and copy the all the swf files into the SAME folder where your Main-Interface movie, the root folder were the ("main swf" and the html file are located).

Given how frecuently you need to export those movies (2 to 5 times: you have forgotten to add something, you need to recompress or update a graphic, you have exported the movie with the wrong Stage-size, suddenly the script doesn't work...), I tend to reconstruct all those content-movies in just one Flash-document. This way I make sure that all external files have the same Stage dimensions and I cut down the chances of loosing files in the Production process.
To do this, select all the timeline in the original fla, copy frames, create a new scene in the destinatiin file, paste frames.

If you follow this method, place each content section in a separate scene.
Export the movies with the "Test scene command", change the name of the automatic document created for the scene, whith whatever desciptive name you need (this is the name that the main Movie will use to call it in the script).

Follow the description of how to use 1 flash project to organize all the external movies: