The tf2demo.mp3 file you have requested: Media / Videos and Trailers / Official Videos / Team Fortress 2 Demo - MP3 - 1.69mb is not available. Perhaps try browsing all files for the game Team Fortress 2 and upload any files you want to share or are missing. This is the only information we could locate:
A cool mp3 of someone form TFS attacking an enemy base. In the background you can hear several different types of guns and grenades going off. Also when a flag or objective is reached you hear a radio type voice (Commander) tell you it happened.