This run is fucking stupid.
It's a TAS (Tool-Assisted Speedrun). Basically the game is slowed down to a crawl which makes it so the user doesn't need a good reaction time. This run was probably in real-time about 10-20 minutes. Not only this, but it was also on an emulator, which is also not allowed for this kind of stuff.
The REAL world record is 4:58 by Andrew Gardikis. No cheats, no bullshit. Speed Demos Archive - Super Mario Bros.