Architects are aware of the fluctuations in the cost of materials due to global demand. The Times takes a look at one link of that global chain that is having a big impact on Midwestern cities: scrappers. The short documentary video “Dismantling Detroit” captures that city’s former manufacturing glory, which now being pulled down and sold for scrap to feed China’s productivity. It’s a brief, sobering look at a complex problem with vast implications for the Midwest’s built environment.