Any YouTube, Vimeo, Kaltura, Wistia, or Panopto subtitles will automatically be brought into PlayPosit when you create the bulb.
You are always welcome to add your own srt or vtt file to the video to add custom subtitles. Instructions here: https://playposit.uservoice.com/knowledgebase/articles/1132915-can-i-add-my-own-subtitles-to-the-bulb.
In addition to the in-line video closed captions, we provide a streaming transcript of closed captions in the right-side navigation bar. This transcript highlights the part of the video you are currently viewing and also allows the viewer to jump to other points of the video by clicking the subtitle timestamp.