It is possible for you to display and play mp3 files on the builder, from what I have been told by one of the Staffies who had a hand in creating the software if you select the 'Media' tab from the top of the deisgn page this will open up the relevant window.
On this new popup you should select 'Windows Media Player' from the drop down list before linking to the URL of your uploaded .mp3 file.










