services amfphp drupalsite flash

I've got a local copy of my site (running on MAMP) that uses flash with the technology and frameworks mentioned in the title working fine on both Firefox and Safari locally. It also works fine locally if I choose the remote path for the gateway url in both browsers ONLY if the site is running locally - but if I upload the swf online it works in Safari but not Firefox.

To recap -
running locally in MAMP at the address http://mysite.dev (localhost/mysite)
gateway URL = http://mysite.dev/services/amfphp/gateway.php
works fine in Firefox and Safari