It is also possible to modify a real arcade machine hardware. And it's also possible to put some visual or aural indicators for player when to press which butt

It is also possible to modify a real arcade machine hardware. And it's also possible to put some visual or aural indicators for player when to press which buttons, so the player would be just following computer's instructions. An ability to sync your actions to background music not provided by the game itself is also a possible avenue for cheating. So the idea that somebody can set a recognisible world record while streaming from home is ridiculous. A proper procedure must involve all hardware and software provided by competition organizers and checked by independent judges.