Watch 123Movies. Filmed on location in seven different states during 1980-1981, America’s most loved and original music genre is the subject of “That’s Bluegrass”. This care-free, fast-moving documentary lovingly examines our home-grown musical heritage from the simple front porch fiddler to famous Nashville recording stars, listening in as accomplished amateurs do some “pickin and grinning” at outdoor festivals and play songs handed down from generation to generation.