I was assuming it was just movie posters and screenshots from online articles/reviews/imdb etc, and not any analysis of the video itself (I might be wrong thoug

I was assuming it was just movie posters and screenshots from online articles/reviews/imdb etc, and not any analysis of the video itself (I might be wrong though - using video would make the number of available input frames grow by orders of magnitude, not that there is a lack of pictures online). E.g. The Shining picture of Jack Nicholson with the door isn't representative of the "look" of the film, but very much an iconic still frame and basically what you see in a Google image search for "The Shining".