Do you watch films on foreign language? If you don't know language perfectly, you probably use captions, but subtitles are not necessary all the time, because you need them for new words only. I have created a Chrome browser's extension for Netflix site, it displays captions after short video rewind. Choose primary subtitles - captions on foreign language, then choose secondary ones - captions on your native language, after that turn off all captions and focus on listening. When you face with unknown phrase, press CTRL key and a movie will be rewound on 10 seconds. Now, you can see primary subtitles and if you don't know some words, press CTRL again, you will see a dual captions. After that difficult video's fragment subtitles will disappear. That's all. Hope it will be helpful for you!