“Summer Time” played by Vesa Asikainen, a Finnish documentary filmmaker.
He used a leaf to perform the beautiful music.
As a Korean dude, I also have experiences of doing a smilar thing when I was a kid, but his level of performance goes beyond my words.
It sounds like a Korean traditional flute to my surprise.
Another thing that impressed me was his attitude when he took a leaf from a plant pot at the k-Culture Center just beside Seoul Selection Bookshop in Samcheongdong.
He looked as if he was asking permission from the plant and the leaf. People are really marvelous.