This is a really interesting piece. The rhythm of the melody is constantly changing, cycling through multiple sequences — which the creator of the video has visualised here — while the pitch content of the melody remains the same. This shifting melody, juxtaposed with the 4/4 pulse of the song, creates a captivating listening experience. You could say that the notes of the melody are essentially constant, while the way that melody is being expressed rhythmically is constantly changing.