In FIDE you can't promote to an upside down rook, or some other non-queen. If you want to promote to a queen, you have to pause the clock and go get one.
So the young guy went to get one, and when he came back the other guy resigned.
Oh I see , so he was going to get an extra queen ! I thought like wtf is he doing stopping the clock and walking off I thought calling the ref or something, but I couldn't find anything illegal there.
https://youtu.be/gyDnhXHwmKA