Not the OP but I would guess it's not that it was unique or surprising, but that it was didactically/pedagogically nicely explained. Experienced devs might find it superfluous since they've already guessed the solution from as soon as the problem is stated, but this is something I could share with a CS 100 student and they'd get a lot out of it.

My initial thought was recording the position in each frame.

Obviously after reading it, it seems obvious. And if I were implementing it, I am pretty sure I would have came to the same solution.

But it was not immediately obvious to me from the title.