A screencap from this movie has already been posted by 'argoman' @ #2 in this thread but here is a clip of Pat Astley and Susie Silvey getting their kit off in the 1978 film 'The Stud'.
Type: MPG, size: 10 MB, duration: 39s.
Link:
http://depositfiles.com/files/yl6c7loo5