I've been trying to use SWFScan and it worked fine on my Flex 3 app, but none of my AS2-based SWFs (built using Flash 8) work. Every time I try to load them I get an error stating:
"The Flash Application was malformed: Malformed data in SWF Header"
The SWFs themselves work fine, so I'm fairly certain there aren't any problems with the files.
We would not be able to answer this without reviewing the .swf files in question. Unfortunately, we don't offer that level of support for this application, as it is a free giveaway. I wish we had a better answer than that. Sorry.