Ah OK - yes you should be able to do it by just moving the *.dll and it's manifest to the Firefox plugins directory. See here:
http://wiki.videolan.org/Windows#VLC_Pl ... Mozilla.29
The files in the "mozilla" directory have been moved to the main VLC directory - they are
npvlc.dll and
npvlc.dll.manifest. Close Firefox and copy those to (or wherever Firefox is installed):
C:\Program Files (x86)\Mozilla Firefox\plugins
Then start Firefox up again and check to see if VLC Web Plugin is there (might be near/at the bottom of the page).
This will probably just crash by itself so becauase npvlc.dll doesn't know where VLC is, so try installing VLC with the Mozilla plugin too to setup the registry entries.
EDIT: If you also put
libvlc.dll,
libvlc.dll.manifest,
libvlccore.dll and the entire "plugins" directory into Firefox plugins directory it should work without installing anything. This isn't ideal of course as you're essentially copying the majoriy of VLC into the plugins folder.
Arite.