I will try again just once more (I'm also waiting for a response from the company who I have addressed these concerns to). If the reported case happens again without any intervention (I had the pleasure of listening to a full volume show for 40 minutes played by a passenger's phone right behind the driver) then I will take matters into my own hands.
Option 1: sitting down right next to the offender and watching whatever they do from very close. If they invited me for a free audio experience then the video experience must be free, as well.
Option 2: I will just sit down right next to them and blast my music at full volume, as well. Above the Weeping World and Winter's Gate are great albums.