‘Thriller’ Is Now in 4K on YouTube

Michael Jackson’s Thriller, is now available on YouTube in 4K.
This is the 13 minute version directed by John Landis.
At the time, Thriller was the most expensive music video of all time.
What does it mean that it is now in 4K? It means it is a high-definition video that has four times the resolution of 1080p HD video.
What is your favorite Michael Jackson video that you could watch over and over?