I just found these while I was trying to safeguard the mp3 files being played inside the Google reader.
var player = document.getElementById('player');
var mp3_file = player.innerText;
# NOT WORKING IN FIREFOX, but in Opera/IE. I need a text version only
player.innerHTML = ''; # throw anything inside it
var embed = document.createElement('embed');
# in [b]IE6[/b], this code is lost in referrer
player.appendChild(embed); # install the player
innerText is an IE proprietary property. Opera copies many of the IE proprietary codes - other browsers do not usually do so. The only IE proprietary property similar to innerText that was considered useful enough for all browsers to adopt it as a defacto standard is innerHTML. Simply substitute innerHTML for innerText and it should then work for all browsers.
embed is also a proprietary tag (admittedly one supported by most browsers). You would probably get it to work better if you instead used the standard object tag that is intended for the purpose. See http://www.felgall.com/flash.htm for two ways to use object tags to embed flash depending on whether or not you need to support antiquated flash versions in IE6.