It is the most popular streaming platform in the United States, with more than 60 million paid subscribers, and much of its original content is in languages other than English. The second factor, they say, is Netflix itself. The first is a 2016 rule from the Federal Communications Commission that made it mandatory for a TV show that has been captioned for broadcast to also be captioned when it is posted online or on a streaming service such at Netflix or Hulu. Researchers credit the shift in part to two factors. Over the same period, as streaming services have replaced network and cable television, subtitles have also gained a stronger toehold on smaller screens, from cellphones to TV sets. The film joined a small group of subtitled films that have broken through to mainstream success in Hollywood over the last two decades, like “Roma” (2018), “Pan’s Labyrinth” (2006), “Amelie” (2001) and “Crouching Tiger Hidden Dragon” (2000), a Chinese drama that earned $128 million, making it the highest grossing foreign language film in the United States. Even before “Parasite,” a thriller about the class divide in South Korea, took off, there were signs that things had begun to shift for subtitled entertainment in the United States.