I like it the most since its video and sound match pretty well. The moving part grows larger while the audio turns more complex and also louder. I can totally feel the meaning of those moving rectangles representing the pitch and loudness. It also provide a sense of space (at around 4:20). When the animation located on the right, the audio also seems to be come from the same direction. I’m not sure if it’s my illusion, or it’s a well implement of synesthesia. Without the audio, this could be just some random animation.
The ‘Piano Form’ by Jesse Woolston has a beautiful 3D animation, but I can’t figure out how those spheres are related to the audio. Sometimes they just don’t make sense. I saw some people’s comments guessing it’s triggered by some specific keys, but I’m not sure about that.