I am thinking of something like "screen caps" term in English. I mean the movie part with a subtitle, as a photo. How can I say "screen caps" / "movie caps" in Chinese?
Generic screen caps in Chinese is
截圖 / 截图. If you really want to specify it is from a movie, you can add "movies" in front, i.e.
電影截圖, or for videos in general
視訊截圖. Usually that is not very necessary.