At many stages of the film-to-video process, noise reduction
can be applied, for a variety of reasons. It is commonly applied to make the job
of MPEG compression easier - a less noisy image can be better compressed than a
noisy image, since randomness is removed from the image being encoded. The excessive
use of noise reduction can manifest as an image which displays the disconcerting and annoying phenomenon of parts of the image
moving independently of each other. Often this can affect faces, making them
appear to float independently of the rest of an image.
Note the back of the chair, particularly against the white sliver of window,
moving independently of the rest of the image.