The player would have a delay of one second (or so) while it played the movie to itself. Then when the movie starts playing the player knows when to bleep based off of the voice recognition.
It could hopefully be a plugin for Quicktime.
It would need a preferences pane with an on/off button so that every time you wanted to turn it off you could do so without uninstalling it.
Ideally made for a Mac.
With enough development it might have the potential to be a plugin for Firefox or something.