This is a tool-assisted speedrun. For more information, see http://tasvideos.org/2691M.html
One of the few N64 titles to be in 2D, Magical Tetris Challenge is another port of Tetris (http://tasvideos.org/1596M.html) , this time featuring Mickey Mouse.
Watch as PoochyEXE completely destroys this short game, racking up as many points as possible before the AI tries to kill itself.