Not a Perl solution: but the Ming-library might be usefull here. From their FAQ:

* Can you manipulate existing SWF files with Ming?
No. Ming is most useful, I believe, in conjunction with the Flash loadMovie command- any dynamic content you need can be loaded into a parent movie..
The Ming source package includes a utility called swf2php which tries to convert an SWF movie into a PHP script which creates the same movie, but it's a bit out of date and incomplete.

But the good news is they have Perl-wrappers too.