The video "To Engineer is Human" is a somewhat outdated video about various structural failures in buildings. Many of these failures were overlooked by the engineer who designed the building. Causes of structural failures can be many things. Sometimes, the design for part of a structure is overlooked, and an error is not detected by the engineer. Other times, a structure may not be built with strong enough, and therefore, collapse. Even nature itself can cause structural failures if the engineer does not compensate for the area his structure is to be built in. Stresses and materials are important in structural failures for many reasons. For example, a certain kind of material may not be strong enough to do something another material can. Stresses on the material itself can also cause the material to break. 

Failure is necessary for future success because our mistakes lead to advances in engineering as well as safer structures in the future. Today, unlike in the video, many engineers can experience this failure with the aid of computers. These computers can simulate the structure, allowing the engineer to fix this before even building a prototype. Having spoken about prototypes, they are also another good way to test for structural failures by testing the scale model's aerodynamics for example.