Nishant Kasibhatla memorizes a 30 digit "random" number at the beginning of the video and recalls it correctly, in reverse, at the end of the video.

He uses number visualization of combinations to do this. (every 2 digit number has an image in his mind that he has practiced substantially in relation)... Similar to Mind Palace.

He did make a few mistakes in the normal recall at the beginning... But it is safe to assume that he did it on purpose (for what reason I do not know), because he has a lot of expertise in it.