Recently someone taught me a neat trick with Charles. I had a SWF that was loaded in a much larger SWF and HTML page, but I didn't want to build these other pieces. I had access, however, to a testing site where the SWF/HTML pages were located, and with this I could use "Map Local".
Map Local allows you to map URLs to local directories. This means that you can test a SWF that should be on a remote site. It's incredibly useful for the large project problem I was having or for debugging problems on a live site.