I got XMMS to work as a plug-in on my old, obsolete system.
I reinstalled RedHat Linux 8.0. I wanted a clean installation, keeping in mind that I would have to patch the RedHat XMMS package.
Sure enough, with a fresh install, XMMS, did not work as a browser plug-in. I had the same problems as before.
I found the patch at Guru Labs Downloads and downloaded the .rpm version for an easy install.
Then, I added the plug-in to my Mozilla browser. Go to "edit," then "preferences." Under "preferences," click on "Helper Applications." Then, click on "New Type." In the box entitled "file extension," type "wav." Then, in the box entitled "MIMI Type," put "audio/x-wav." Next, type either the location of your XMMS application, in my case "/usr/bin/xmms," or just type the application, "xmms."
Next you have to direct the browser to use the plug-in. Click on an online .wav file such as:
You should get a dialogue box which asks, "open using /usr/bin/xmms," or "download file." You want to play the file, not download it, so click in the circle for "open using /usr/bin/xmms." If it says something else in the "open" option, you need to click on "advanced." That will take you to another dialogue box. In the box entitled "MIME type," put in "audio/x-wav." In the box entitled "handled by," click aplpication and type either xmms, or the application's location (probably /usr/bin/xmms). Click "Okay," and you're ready to play .wav files through your browser. Such files could be songs, sound effects, or news reports, etc.