[Retr0id]

Even with a microcontroller, doing frame-perfect inputs is tricky because you don't have anything to sync off of - even tapping into the vsync signal from the video output is an imperfect reference because there's no guarantee that the game engine is actually synced with it (although I have no knowledge of SMM, maybe it does work better than I expect)

[a_t48]

You can start off with a start input to unpause the game, for instance.

[Retr0id]

That doesn't solve the problem, in the general case (it might work acceptably well in practice, though)

[ikiris]

if your controller has such loose timing that you can't match a 10ms window reliably, you're doing something very wrong. '

[lmm]

Match a 10ms window how far away from your last sync point? Every clock has a drift rate.

[themoonisachees]

I get where you're going, but also consider the level is 17 seconds long. It's not unreasonable to think he just ran it a few times until the clocks decided to cooperate.