Get all the words from the subtitles files, and add a feature of showing the rarely used words (hard words), so if someone wants to watch a movie in English and he isn't proficient in English, he would choose what movie he wants to watch and then memorize the hard words that are in the movie/series and then watch the show, and understand it without pausing to translate (if he wants subtitles in English in that case a language that isn't his mother language).
You can get how used (easy) a word is by getting how many results it has in a Google search or if you want you can research it with smartness.
In OpenSubtitlesPlayer, add a clearly evident button below the movie called: "Hide time", and then it toggles to: "Show time", for when one wants to watch a movie and he's in its 2nd half for example and he doesn't want to know when the movie would end as that may be a spoiler, or even from the beginning he doesn't want to see time as a spoiler and also to not focus on time and forget time as that may be a distraction, any time he wants to see or return for an always visible time he would press on the now called: "Show time" easily visible button, this feature can be made not enabled by default and would be able to be enabled/disabled is settings.