Doesn't look like it's PBS production (though on public TV), it's a pledge week item.

Here's an article: John Sebastian Presents: Folk Rewind. "Sebastian is the host for this salute to folk music of the past that includes legends of the folk world reunited to sing some of their greatest songs."

Many stations carry this blurb: "A John Sebastian-hosted celebration of the 1960s' folk-music boom, featuring archival footage of the era's top performers and modern-day performances by Barry McGuire, Roger McGuinn, the Chad Mitchell Trio, Chad and Jeremy, and Jesse Colin Young."

Here's a YouTube: click

~ Becky in Long Beach