PBS distributes Keeping Up Appearances .
It is a nonprofit organization and the most prominent provider of educational television programming to public television stations in the United States , distributing series such as American Experience , America 's Test Kitchen , Antiques Roadshow , Arthur , Barney & Friends , Clifford the Big Red Dog , Downton Abbey , Finding Your Roots , Frontline , Keeping Up Appearances , The Magic School Bus , Masterpiece , Mister Rogers ' Neighborhood , Nature , Nova , the PBS NewsHour , Sesame Street , Teletubbies , and This Old House .