Dimp is a very clever video manipulation player that lets you browse and view video clips just by dragging on the footage itself. You need to watch the videos directly to get a feel for the tech, but it’s very cool. You can download the free player and have a go yourself from here.
Although the video clip itself is not modified, dragging an object constrained to a trajectory is similar to dragging a slider. The slider’s thumb will never stray away from its predefined trajectory, yet we all agree it is being directly manipulated. Whether it is true direct manipulation or not is actually an ill-posed question. On computer screens, where everything is just pixels, you are never physically manipulating objects. Direct manipulation is always an illusion produced by having user’s gestures match the resulting motions on the screen as closely as possible.