The silhouette videos above are from the New Jersey Film School which offers hands-on classes for kids and adults.
Silhouettes have been used since the early Egyptians and Greeks. Silhouettes are related to shadow puppetry from ancient Chinese. The art form became especially popular for portraits during the mid-18th century. And then photographers and later filmmakers used silhouette shots for their beauty and effect.
To make a silhouette of a person, light the background, but not the person. Keep the subject far enough away from the background so there is no light spill on the subject. For the most action, place the camera where the silhouette of the actor changes the most in the action. If, for instance, the actor is pointing with his arm, the camera should shoot the profile to maximize the action.
The silhouette videos above were probably made with a green screen which makes the background color replacement easy. What kind of video you can create with silhouettes?