When watching Inglourious Basterds (2009), a "patched" subtitle version is often necessary because only about 30% of the film is spoken in English. The rest features extensive dialogue in German, French, and Italian.
to "burn in" the forced subtitle track directly into the video file so they are always visible and cannot be turned off. Plex/Media Server Fix
When you watch a movie in English that contains foreign dialogue, the subtitles for that specific dialogue are called forced subtitles. They are distinct from the "Full Subtitles" track (which captions every sound and word for the hearing impaired).