totem with both flac and mpeg use flags will not play mp3. The totem nsplugin registers itself to play mp3 so playing audio from the net does not work.
Ater re-emerging gst-plugins-mad-0.10.3 Totem can now play mp3 audio interactively. There is still a problem with the nsplugin. http://akamai.infoworld.com/weblog/daily/archives/IFW_Daily_09-13-06.mp3 is the infoworld daily podcast from yesterday as shows the problem. If I go to this site in firefox I get a "cannot find plugin error". If I enter this url in play location in Totem, it plays.
It plays fine for me in my browser: epiphany.
Please test and reopen if you can reproduce with 2.16.2-r1