Rob Ely from Idaho sent me a recording of himself playing this Swedish tune on a hammered dulcimer, asking if I could identify it. He had a slightly garbled version of the name, which helped me locate it, knowing that "Orsa Spelman" is the name of a well known band.
I liked it so much that I've learned it and made a harmony part. It comes in the second time through the tune, and is played off-camera.