My bug report to the mozilla developper team has been defeated with
"irrelevant because no web server can handle such huge uploads".
Firefox still has such a bug... BUT in a new kind of implementation! :-)
Firefox upto version 7 will not send any byte when one tries to upload a
file > 2 GB.
Whereas Firefox 7 (and later) now sends a full HTTP POST upload with the complete file, but it fails in calculating the correct Content-Length header. Here it still has a 32 bit overflow bug.
A standard webserver will fail when the Content-Length header is wrong. It cannot read more then the announced bytes. But F*EX has its own webserver which ignores this header!
This means for Firefox users: NO MORE LIMITS!
All other web browsers (besides Google Chrome) I am aware of still have a stupid 32 bit bug.
(*) Of course the F*EX clients fexsend and fexit do not have any limitation and they can resume an interrupted upload.