If you caught AGDQ 2016 you might have seen a TAS run of Super Mario Bros 3 that showed a secret backdoor that accessed Color-A-Dinosaur which was programmed into the game. Of course some were quick to say that is was fake, but apparently it is real.
This video was posted by Lord Tom from the unmodified run that took place over 2 weeks ago. Lord Tom noted that the version those saw at AGDQ 2016 was slightly modified, but only at the very end of the game. That run was used by TASBot using an unmodified NES and Super Mario Bros. 3 cartridge. So yes, both runs were not hacked versions of the game and both used an original, unmodified version of the game.
For those unaware, TAS stand for Tool-Assisted Speedrun which is a controller input sequence that constitutes the performance of a video game. This allows them to push buttons perfectly and in some cases access options that would otherwise be impossible with the human hand such as the ability to push both the left and right controls on the d-pad.