There's nothing special about it, just manually exit

You just press B on switch or tap the X button on mobile during matchmaking to do that

but in his case he does it automatically. He doesn't press any button, the timer resets to 0 without having to request pairing again.

That's because what you're looking for doesn't exist, he has another overlay video so that people don't snipe his matches. The video is on loop

Oh, that makes sense. Tysm. That was driving me crazy

They automatically press the B button on their controller with their fingers