I’m sure street musicians get approached by passers-by all the time and asked if they can join them for one song. Also I’m pretty sure most of them hate it because just because you think you can sing doesn’t necessarily mean you really can.
I have no idea why this performer let this lady perform Hallelujah with him, maybe because she was good looking, but her voice stunned not only him, but everyone who clicked Play on this video. I mean the girl can sing. Her powerful vocals and his beautiful voice complement one another for one of the most beautiful renditions of the song I’ve heard.