Black and white is the minor key of photography.
The first half of the video is designed to show the quirky, colorful, cheerful nature of Paradise Garden. The second half shows how the same place, the same photos, the same song can be somber and eerie, just by changing one aspect of how you perceive it. I faded the series to black & white and played the melody in the minor key, and suddenly, the charming garden is gloomy.