If it’s merely about turning an swf file into an mp4, there’s more than a few tools out there. But if it’s about a .fla then things get a bit more complicated. Only older versions of the Flash editor can do that – and Sothink SWF Decompiler (as far as I know).
Not quite on topic, I realise. But it’s something I was recently messing about with. My conclusion – don’t use Flash if you can. Lol.