David Brooks in the Times blogged on Mr. Murray's new book, suggesting that the white upper and lower classes have diverged greatly in mode of life and social mores since the 50's. Specifically, the top 20 percent or so don't divorce, while the bottom don't marry or they divorce. And so on.
Here's a 1957 short film, not a documentary, on social class in America, part I and part 2. (Hat tip to someone, maybe Tyler Cowen.) What is interesting is the assumptions the creators make, which are apparent in retrospect. The discussion of class is a bit more open than I'd expect today, though that might be because it's apparently a sociologist behind the film. ("Ascribed status" and achieved status, mobility.)
There are 3 kids, upper, middle, and lower class. All 3 kids are boys, their class is defined in terms of the occupations and backgrounds of their fathers, and they all come from unbroken homes. All 3 graduate from a public school, though one goes on to the Ivy League, and graduation is an achievement for the lower class boy. All 3 fathers wear suits for the high school graduation.
The upper class boy graduates and works for his father's factory, the lower class is a gas station attendant training to be a mechanic The middle class boy follows his dream of art to NYC and an ad agency--horizontal mobility leads to upward mobility. The city is seen as the route for upward mobility because standards are different.
Seems to me that the social structure was more stovepiped in the 50's; each town had its own lower, middle, and upper class. Since then the big banks have absorbed the local banks, the big real estate companies have absorbed the locals, the restaurant chains have ousted the local diners, the local auto mechanic is a dying breed, etc.
So parts of the film seem to support the Murray thesis while others don't.