Streaming Platforms with Firefox PiP Subtitle Support

This article provides a quick overview of the video streaming platforms that support subtitles and closed captions inside the Picture-in-Picture (PiP) window of the Mozilla Firefox web browser. While standard browser PiP modes historically stripped away text tracks, Firefox resolved this limitation by natively supporting the WebVTT format and engineering custom rendering adapters for major streaming services. Below is the breakdown of streaming platforms that successfully display subtitles in Firefox's PiP mode, categorized by how they render the text.

Platforms Using Custom Subtitle Rendering

Most major commercial streaming services do not use standard HTML5 video text tracks. Instead, they use complex, custom-built HTML and CSS overlays to display subtitles for Digital Rights Management (DRM) and styling purposes. Because these custom subtitles do not naturally transfer to a Picture-in-Picture window, Mozilla created site-specific adapters that read the custom subtitle data on the webpage and re-render it inside the Firefox PiP player.

The following platforms are explicitly supported in Firefox PiP through custom subtitle rendering:

  • YouTube: Supports both auto-generated captions and user-uploaded subtitle tracks.
  • Netflix: Supports standard subtitles and closed captions across its entire catalog.
  • Amazon Prime Video: Renders standard subtitles inside the PiP window.
  • Disney+: Supports multi-language subtitles and closed captioning.
  • Hulu: Displays standard platform captions in the popped-out window.
  • Max (formerly HBO Max): Supports standard subtitle tracks.
  • Funimation: Renders anime subtitles directly in the PiP window.
  • Hotstar (Disney+ Hotstar): Supports regional and English subtitle overlays.
  • SonyLIV: Renders custom site captions inside the PiP player.

Platforms Supporting WebVTT Natively

WebVTT (Web Video Text Tracks) is the World Wide Web Consortium (W3C) standard for displaying timed text in connection with the HTML5 <track> element. Firefox natively supports WebVTT in its Picture-in-Picture window. This means that any website adhering to this universal web standard will automatically have working PiP subtitles without needing a custom update from Mozilla.

Major platforms and video players that utilize native WebVTT and work seamlessly with Firefox PiP include:

  • Vimeo: Works on all videos where the creator has uploaded a standard .vtt caption file.
  • Coursera: Supports interactive transcripts and lecture subtitles in the PiP window.
  • edX: Renders educational video captions natively.
  • Tubi: Uses standard WebVTT tracks for its free, ad-supported movie catalog.
  • Dailymotion: Supports native text tracks on applicable videos.
  • Plex and Jellyfin (Web Apps): When streaming personal media in Firefox, if the subtitle format is .vtt or .srt (which the server converts to WebVTT on the fly), the subtitles will appear in the PiP window without requiring server-side video transcoding.
  • Open-Source HTML5 Players: Websites utilizing standard players like Video.js, Plyr, or JW Player (when configured to use native HTML5 text tracks) will automatically display subtitles in Firefox PiP.

How to Ensure Subtitles Appear in Firefox PiP

Regardless of whether a platform uses WebVTT or custom rendering, Firefox requires the subtitle track to be active on the main webpage first. To use them, start playing your video, turn on the Closed Captions (CC) or subtitles using the streaming platform's native video player controls, and then click the Firefox Picture-in-Picture toggle. Once the PiP window is open, you can also adjust the subtitle font size directly using the settings cog icon inside the Firefox PiP player.