This plugin is Fixed and works
I went ahead and fixed this plugin , it now works on 2.1 also. I fixed the js which was all messed up too.
The way this works is you post the link to the mp3 file into the discussion as you would any other link and this makes a small but functional button next to the file so it can be played on the page. It also ads the play button to the attachment thumbnail of the mp3 linked file if you upload the mp3 content to your forum.
you can see it working here
just install this version I attached as you would any other plugin and enable in the dashboard.