There's a good chance that one of those two arranged it themselves. You can either transcribe it or arrange one for yourself. You may be able to ask the person who uploaded the video if they have a copy of that duet.
I'd say write one out for yourself. It's not too hard a tune to arrange, and it's good practice.
has the sheet music....just scroll down to the second tune. If i remember correctly, one of the guys in the vid is playing the top notes of the treble staff and the other is playing the bass clef part.