Go to the woods of Kyushu, Japan. Engineer a massive xylophone (or is it a marimba?) to run down the slope of a forested hill. Take a wooden ball, place it at the top of said instrument, and push it. What do you get? Bach's treatment of a traditional church hymn! Namely, "Jesu, Joy of Man's Desiring."
And, all this for a Japanese commercial for a kidney-shaped smartphone with the tagline, "Touch Wood." I may be late to the party on this one, but when I think of all the time it took to set this up, the precision and measurements used to adjust it and actually make each piece, and how many takes the film crew shot, it continues to inspire even if it's a year old.
And, here you can see how it was made: