While the Mast Camera (MastCam) serves many of the same purposes as its predecessor (the Panoramic Camera) on the Mars Exploration Rovers, it also features some important new capabilities. The camera is able to acquire data - including video - at a high rate of speed and store it in its own memory. Compression and sampling of images is performed entirely using only MastCam resources, not taking up memory in the rover's "brain." The stereo multispectral images, in conjunction with high-definition (HD) video and stereo video, allow enhanced scientific studies of landscape physiography and processes, properties of rocks and fines, and views of frost, ice, and related processes where applicable. The video capabilities also provide unprecedented observations of atmospheric and meteorological events including clouds, dust-devils, wind transport of surface materials, and rover trenching.