The video shows a 3D animation of a human knee joint. The animation begins with a healthy knee joint and then shows the cartilage beginning to break down and wear away. The cartilage is shown in red, indicating damage, while the healthy parts of the knee are shown in beige. The animation progresses to show the cartilage completely worn away, leaving only the bone. The video provides a clear and detailed visual representation of the process of cartilage wear and tear in the knee joint.