Firefox 3.6.* Ogg Vorbis handling

With Firefox 3.6.*, Ogg Vorbis files are being handled only by plugins. 
  Why??
Using Mac Firefox, I set 'browser.download.pluginOverrideTypes', as well 
as 'plugin.disable_full_page_plugin_for_types' to include 
application/ogg.  I also changed the setting for Ogg files in 
Preferences > Applications to 'ask first', after adding both VLC and 
MPlayer to the application list.  All that was ignored and Firefox 
insists on using a plugin. I tried setting the Ogg files setting to open 
with VLC, and then MPlayer.  That was ignored.  I tried setting it to 
save the file.  That too is ignored.   If I set 'media.ogg.enabled' to 
false, Firefox tries to use the Quicktime plugin, which does not handle 
.ogg files.
I looked in the mimeTypes.rdf file, and that shows the settings exactly 
as I set them up in Applications.

Windows Firefox does not list Ogg in the Applications list at all, 
though I have Irfanview set up to play Ogg Vorbis files.  I have the 
same plugin override & disable settings as for Mac.  If I set 
media.ogg.enabled' to false, the VLC plugin plays the file.

What is going on with Firefox?  How was the use of helper applications 
completely disabled for that content-type?  Is there any way to reverse 
that?