From Luther B. Fuller:
QuickTime Onetime Playlist or QT1P, when launched, will hide QuickTime Player, then proceed to play its open audio documents. Audio documents may be any audio files or video files having a sound track. If QuickTime Player is not active or has no open documents, then QT1P does nothing. When each document finishes playing, it is closed. When all documents have finished playing, both QT1P and QuickTime Player quit.