This speedrun is made using a PC emulator with savestates and slowdown. It's meant to show the game pushed to its limits and that's why it'll blow you away in the Bowser stages!
Here's a list detailing games that are so difficult, or expansive, or demand such a level of time, effort, and skill, that they are known forever for their demands of a player. This list shows the Top Ten Greatest Achievements in Gaming.
After the 1996 release of Super Mario 64, magazines for years mentioned Super Mario 128 that would feature both Mario & Luigi for release on the N64 or its 64DD add-on. In an interview with Level3 Magazine in Sweden Mario creator Shigeru Miyamoto mentions the game.