There is an amazing youth movement going on in New Orleans backing a resurgence of the brass-band format as a malleable form of expression, with the success of Troy “Trombone Shorty” Andrews, The transformation of staid Preservation Hall into a fount of musical collaboration, this year’s Grammy won by The Rebirth Brass Band, and sparkling new recording from both The Dirty Dozen Brass Band and the Soul Rebels Brass Band just tip of iceberg with roughly a dozen new, youth-oriented brass bands in various forms evolution and achievement. Something similar has been going on in Cajun country in southwest Louisiana, centered in Lafayette, Louisiana, for the past decade and the leading bands — like Feufollet (FOO-FILLAY, or depending on where you live, FOO-FIL-A) — are moving closer to the edge of breaking out nationally and internationally. The band’s set on Friday morning of the second weekend of Jazz Fest perfectly illustrated their potential. Playing to a large crowd more interested in listening that dancing and whooping it up, the band showed off their traditional Cajun credentials (all in their mid-20s, they’ve been playing together for more than dozen years) before breaking out the mind-blowing eclecticism, which included their version of The Beach Boys’ “Heroes and Villains” (major fans, the tune’s been in their repertoire for about six months), a Cajun French version of a tune by cult favorites Big Star, and “If I was a Farmer,” a tribute to fellow Lafayette rockers Brass Bed with whom they previously collaborated. Leader Chris Stafford is an A-list electric guitarist recently turned engineer/producer, while vocalist Anna Laura Edmiston lends a critical dimension to three-part harmonies reminiscent of the earliest Byrds records. In fact, the band’s deliberate experimentation, youthful optimism, and range from soft and pretty folk-rock to snarling, straight-on folk-rock mostly recall the best bands of the mid-1960s, before the influence on the music scene of multinational corporations.