Pass Parameters From HTML To The SWF File?

I've created a very simple video player that I want to use with many different FLV files on my site. Rather than packaging SWF files with each FLV, I'd like to just design one SWF file and have the corresponding HTML file pass the URL of the FLV as a parameter to the SWF. I've read a lot about passing in parameters from HTML to SWF using AS3, and it seems pretty straightforward.  Here's an example of the code I created using Flash CS3 and ActionScript 3.0:
 
this.loaderInfo.addEventListener(Event.COMPLETE,loaderComplete);
function loaderComplete(evt:Event):void {
//traceText.text = "Loaded";

[Code]....
 
Note that I'm using the variable "userName" to pass the parameter.  Eventually I'd use a variable like "movieURL" to convey the actual URL of the FLV file.  In any case, when I run the code, I get ... nothing!  Nothing but a blank text box.  Both the HTML and SWF files are on my local machine.
 
If I uncomment the "//traceText.text = Loaded" line, the text box says "Loaded", which would indicate that the event listener is functioning properly.