Blurring out a face, which moves continually

When blurring out a face who does not want to be recorded, is there any method involving directly dragging the blur on the video as it plays? The closest thing I seem to find is a method involving Event Pan and Crop, creating a mask, and adjusting the position of the mask, by creating a new keyframe for each position.





In my dreams I could just play the video and drag the little blurry spot around to keep it on the face, while the video is playing....