Xubuntu doesn’t come with necessary codecs pre-installed to play mp3 files due to some legal restrictions in some countries. To be able to play MP3 files in gmusicbrowser, install the
gstreamer0.10-plugins-ugly package using terminal emulator. Open terminal and execute the following command:
sudo apt-get install gstreamer0.10-plugins-ugly
After this is complete, you’ll be able to play mp3 music files in gmusicbrowser. Enjoy!