mozilla-plugin completely fails in firefox

I am seeing what looks like the same behaviour in Windows, so either my setup is messed up or this isn't a Linux-specific problem. More precisely: I'm running Firefox 2.0.0.3 on WinXP SP2, using VLC 0.8.6a. Pointing my browser at an Ogg Vorbis file (served with content-type application/ogg, content-disposition inline, proposed filename ending with ".ogg") produces a page that's entirely black except that it says "(no video)" in the middle. (Yes, "video", even though the file in question is actually an audio file.) This isn't a transient thing; it isn't just waiting a while to download enough of the file and then recovering.

If I don't install the Firefox plugin, then pointing my browser at the same file launches the standalone VLC application, which plays the file with no difficulty at all.

Just to add: uninstalling 0.8.6a and installing 0.8.5 instead makes it work. (At least partly; the music plays, and I have a blank white window with no sign of any controls. I don't know whether the plugin is meant to have any features beyond just playing the media it's given, or whether were were meant to be some controls to fiddle with. If the latter, then something isn't quite right for me still.) So, anyway, this seems to be a regression relative to 0.8.5. I haven't tried 0.8.6.

Hmm, OK, so it seems that to get any controls I need to write the Javascript myself. So I did, and now Firefox crashes when I view the page with those controls on, and since trying that I now find that the plugin seems to be misbehaving in all sorts of other ways even without any Javascript (e.g., not playing anything, making Firefox crash, ...). This is all with the version 0.8.5 plugin and it seems that things have changed somewhat since then (as witness the fact that the 0.8.6a plugin simply doesn't work :-) ), so it's probably at most marginally relevant.