I mentioned at the TPG Webinar on Flash that there is a way around the issues with focus trapping in Firefox. My friend and accessibility-colleague Michael Jordan has developed a simple example that shows how to get focus in and out of Flash content in Firefox (using the SWFFocus class). Also in this example he shows how to make links that are not buttons, but use the MSAA link role. This has always been possible, but usually people use the button role.
Give this a try and let us know if it works for you or if you have any suggestions for improvements.
Demonstration test file
Demonstration test file, with HTML links also (added 8/18/2009)
Download demonstration file