A bunch of people born in the 1970s discuss two films from that decade about young people coming of age: 1973’s “American Graffiti” and 1979’s “Breaking Away.” The first is a film (set in 1962) featuring young people driving around a northern California town on the last night of summer before reality sets in; the second is about young people riding bikes (and swimming in a quarry) in Indiana. The first comes from the future director of “Star Wars”; the second comes from the future director of “Krull”. Both are full of faces you will recognize. And both have interesting...