Create a high-resolution, realistic close-up video capturing the detail of a human foot walking on a natural surface. Focus on the texture of the skin, slight movements in the toes, and the muscles flexing with each step. The foot should be well-lit to showcase intricate details and shadows, as it moves slowly across a surface like sand, grass, or dirt. Natural ambient light should create soft highlights and contrast on the skin, giving a lifelike look and dynamic realism with each step forward.