Hi, I am trying to get my old Panasonic gs50 to work, too, and have done all of the troubleshooting I can find to no avail.
While I was looking for the answer, I did find this, the answer to your question, I am new too so it was a cool thing to find...
go to finder, go to applications, go to utilities, go to system profiler, go to hardware, go to firewire,
and that will tell you what the comp sees coming into the firewire port.
With my vid cam, it sees nothing!
hope this helps, if you figure out why your cam is not working, let us know, aloha, C
emac Mac OS X (10.4.4)