Self describing. Obviously AI or TAS runs don't count. It has to be mainstream version of the game on the NES.
From HeliosRX on Reddit:
https://www.reddit.com/r/technews/comments/18xhg9s/34_years_later_a_13yearold_hits_the_nes_tetris/
"As far as I know, the crash is caused by clearing specific numbers of lines at once on specific levels. If you have a spreadsheet of where these crashes occur (for example, clearing a single line on level 157 which is what happened here), you can theoretically avoid all of the crash triggers and go all the way to 255, which is the integer limit for the level. This has been done with a tool-assisted speedrun and the result is that the game loops all the way back to level 0.
Is it humanly possible to do this? Theoretically, yes, but there's also a nasty bug later down the line that requires you to clear 800 lines instead of 10 to progress a specific level, so you're looking at over 3000 lines cleared in order to get there. That's 2-3 hours of really fast and precise Tetris while navigating through bugged (and nearly invisible!) color schemes and crash triggers, so it might be a while before we see serious attempts at it.
In this case this was a race to the world's first kill screen crash, which can happen at level 154 or 155 at the earliest IIRC.