If you have Quicktime plugin for Firefox, annoyingly enough, Quicktime takes control and becomes the default mp3 player for your browser and leaving no option whatsoever to change the default mp3 player. Even if you change the Tools -> Options -> Applications settings to change the default player, it will have no effect as Quicktime has already Hijacked this setting from users.
Now, we go brute force and restrict these kind of plugins to take such controls in the future:
- Go to about:config
- Type ‘plugin’ in the filter box (minus quotes)
- Look for ‘plugin.disable_full_page_plugin_for_types’
- If it already exists and contains a value, add ‘,audio/mpeg’ to the end of it, otherwise just change the value to ‘audio/mpeg’
- Fully close Firefox, wait a few seconds for it to clean up and die
- Launch Firefox again.. click an MP3 link..
voila! it does whatever you’ve specified in your Firefox Options -> Applications.