Murry Lerner's film "Festival"is a cinematicsynthesis of four Newport Folk Festivals that depicts the crucial years of transition for the art of folk music.Performers range from 60's folk legends Bob Dylan and Joan Baez to country artists like Johnny Cash to traditional American folk artists such as the Georgia Sea Island Singers.The range is also from the huge-priced professionals like Peter,Paul and Mary to the authentic folk dignity of Son House and Mississippi John Hurt.Joan Baez,Donovan and Judy Collins are all on view,as are Pete Seeger, the Ed Young Fife & Drum Corps.