ok i wasnt planning to comment this but since so many people are asking, the music in the video is called "Memento Mori" by Mudeth. its actually from the Antibirth mod OST so be sure to check it out.
I lost 99999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999 Brain cells watching this