It's also one of the standard contradance waltz tunes; I've probably danced to it a hundred times. It sounds period and Appalachian, probably because it was composed in the style of a Scottish lament -- Celtic music infuses a lot of the Appalachian tradition.

The video itself is cool. It's quite clear that after 4 years of fighting, the South's resources were running out and the defense collapsing. Defeat was inevitable -- we could outlast them.