It is in Plex Web, hosted version, when you choose subtitles. It is not specific to Firefox. I’m using Chrome.
This was the first I’ve seen of it. I did not see it mentioned in any Plex Web announcement.
It works for uploading SRT subtitles (the only type I tried). The subtitles are not uploaded to the same folder as the movie. I haven’t searched, but guessing they’re in the same location as where the “Search…” function puts them.
