The song is called "Below," and I found myself listening to it over and over again after I found a post by Tom Remington about it on the Black Bear Blog.
In addition to posting this video, Tom posted some interesting info about accounts of Flagstaff memories, including this:
In the months before it was to be flooded, all improvements and repairs in the whole town were stopped. What was the use of painting a house if it were to be covered with water in six months? Why repair anything when the whole village was to be wiped out? So, week by week, the whole town became more and more bedraggled, more gone to seed, more woebegone.In addition, one of the commentators, Richard Paradis, added an article which is well worth reading about another Maine town that, while not drowned, was emptied out and left, graveyards and all, because of another project, near Frye Mountain. Click here to see the post. Mr. Paradis' comment is #3 below the original article.