Captain Birdseye, that's very interesting. I've never even seen a dulcimer before, but am I correct that it's basically a modal instrument where you play melodies against a drone? It does sound like Carthy's doing this, definitely.

In this case, what makes the song seem challenging to me is not the left hand (although there's a tricky phrasing bit in the slide from 11 to 14), but the right hand technique and the way the rhythm fits with the melody line. Martin Carthy has a thumb you can set your watch to.