This is a tool-assisted speedrun. For more information, see http://tasvideos.org/4313M.html. TAS originally published on 2020-10-25.
Bowser has kidnapped Peach again, but this time, Mario's hoarding tendencies are kicking in. He's grabbing all of the items in the kingdom, even when he doesn't really need them.
In this movie, the aim is to complete the game while collecting every possible item without dying, doing so as fast as possible.
DaSmileKat manages to improve on the previous movie (http://tasvideos.org/3648M.html) by 1.36 (82 Frames @60.1 FPS) seconds through careful optimization of almost every level.
