I have the FDOM working well using mp3 and the built in player on the frontend. If I upload the file in the Popup then it works perfectly however if I add mp3s to the page that have already been uploaded (I ftp'd them up) then the player doesn't get included for those file in the frontend.
I don't know exactly what mojo you're using to upgrade the File class to MP3 class but it appears to not work when the files aren't uploaded in the popup, I added an echo to the Player function but it didn't show up so I imagine that the function is'nt being called.
Hey yea just had a bit of a poke around - the upgrade code is only in the handleswfupload function and so i just edited the database so that those files had the MP3 class and now everything works swimmingly :)
Not that I need it anymore but you might want to look at including it in the file import.