What about IMDB making this service...?

What about a website that processes subtitles' words in movies and TV shows in English, and publishes the not common words (hard words), so when one who speaks for example English not perfectly wants to watch a movie/series episode in English with English subtitles, he enters this website and enters the name of the movie and learns the hard words in it and then watches the movie without needing of pausing to translate hard words he/she doesn't know the meaning of and maybe ruin important and cool or funny moments while pausing to translate, and he can understand the movie and also improve his English. However, there's always the small chance of the risk of spoilers by knowing the words from the movie.