ok yeah...that's easy if you know your var..but can you do
file.swf?variable=<?php echo $some_var ?> to get a dynamically generated variable in there...THAT would be cool as hell...and would solve a problem that I'm actually havign at the moment.
I tried to do it with JS but the claimed integration of js with Flash is a little overestimated...in 3 days I couldn't make it do anything.