At the risk of sounding like your grandpa, I will remind younger readers that there was a time when a very high percentage of Americans were watching the same thing at the same time. Annual TV traditions often included gathering for a family-friendly film like “The Sound of Music,” which was once such a staple of the culture that your average American could probably sing a verse of “Do-Re-Mi” or “My Favorite Things” if asked.But if you need any reassurance that “The Sound of Music” has earned its status as a legendary musical honestly, you’ll find it in the North...