Someone left this comment on youtube, and I think it sums up the video perfectly:
"I got this description from someone else, but I think it sums up the video pretty well.%uFEFF The beginning of the song is slow, which represents Michael's childhood. It then becomes faster and more complex to show how rapidly his fame was increasing. It slows down again to illustrate recent years when Michael's fame essentially slowed down again amidst the trials and fewer album releases. The last of the song represents the present, when he announced his comeback, and stops abrubtly at his death."