A spoiler alert – Warning – scroll down and the movie is revealed.
The game started with drawings of pool pump diagrams and insects and than: “why not add a hidden movie for extra fun?”
The hidden movie is “Phantom of the Opera”, 2004, by Joel Schumacher. It is the boat scene where the Phantom sings to his “angel of music”. In this case he is a just a shadow on a residential pool surface although his mask is tangible and floating at eye level.