Sentence:  "Careful viewers have long observed that in the movies, one can not only watch but read cigarettes like <WSD>subtitles</WSD> — translating the action on the screen into another language which the camera registers but rarely foregrounds, a part of the thickness of the medium which is almost never brought into focus. […] The cigarette in the scene serves as a subtext, a mute caption or <WSD>subtitle</WSD>, sometimes accompanying, sometimes contradicting or diverting the explicit premise of the action or the open meaning of signs." 
Meaning of the word marked with <WSD> tags:  Textual versions of the dialog in films, usually displayed at the bottom of the screen.