How to extract flash files from pdf file?

This is really an Acrobat question.  This use-case isn't something that the Flash team deals with.  At the point that we're playing a SWF, it's already a SWF, and the PDF file format is complex, to say the least.

That said, the PDF specification is publicly documented.  In theory, you could extract the bits of the embedded SWF file, but you'd need to be comfortable with reading a large technical specification and manipulating binary files at the bit level.

I'd normally move this post over to one of the Acrobat-related forums for you (I think your best chance of getting an answer is there), but for some reason, I don't seem to have permission to do that.

If you get lucky, a Google search will turn up some reasonably priced third-party tool that parses PDF and extracts any embedded child assets.  I'm not positive that it exists and don't have a specific one to recommend, but these are the kinds of helper tools that independent developers often write.