The video discusses the different forces that act on the earth's crust and how they cause deformation through various mechanisms. Compression causes squeezing and increases density, tension causes pulling and decreases density, and shearing causes twisting. These forces result in fracturing, faulting, and folding of rocks in the crust. Fractures are cracks, faults are cracks with lateral movement, and folds are bends in rock layers. Anticlines are upward folds and synclines are downward folds. Various factors like temperature, pressure, rock type, and rate of force application determine whether rocks fault or fold when subjected to deformation.