Greasy Fork

updated version info - forgot to do that

fixed bug that caused player not to load

made some changes for stabiltiy

Rebuilt from the ground up again.
Volume slider moves now when you change volume.
Works better on Firefox now, though this was build for Brave browser.
If it doesn't work on Firefox, press T, F5, should work from then on until you clear the cache.

Improved OSD

Changelog

1.4.0

• Global volume control:
  • ArrowUp / ArrowDown now control volume even without clicking the video.
  • Shift + Arrow adjusts in larger 10% steps.
  • M toggles mute/unmute.
  • A minimal on-screen overlay displays the current volume or mute state.
• Input-aware: Volume controls are disabled while typing in input fields, comments, or the search box.
• Seamless integration: Feature is integrated directly into Theater Fill layout with no new UI or configuration.

1.3.0

• Exclude https://*.youtube.com/embed/* and https://music.youtube.com/* via metadata rules.
• Add @homepageURL, @supportURL, and @icon metadata fields.
• Maintain fullscreen-only header cover behavior — activates on entering fullscreen and reverts on exit.
• Stateless behavior: no Tampermonkey menu or stored preferences.

1.2.0

• Removed Tampermonkey menu toggle and all localStorage persistence.
• Header cover is now automatic and only activates in fullscreen mode to avoid layout issues.
• Listen to fullscreenchange events (plus webkit/moz/MS variants) for broad compatibility.

1.1.0

• Introduced Tampermonkey menu command to toggle header cover manually.
• Persisted preference using localStorage key ytf-cover-enabled.
• Minor internal cleanup and consistent version log messages.

1.0.0

• Initial release.
• Automatically enables Theater mode on watch pages and resizes the player to fill the viewport height.
• Supports both ytd-watch-flexy and ytd-watch-grid layouts.
• Removes ambient cinematics that interfere with sizing.
• Calculates header offset dynamically and scrolls to top for proper video positioning.
• Re-applies layout fixes on navigation via YouTube's single-page app (SPA) system.
• Included optional header cover logic (disabled by default, no UI exposed).

Changelog — YouTube Theater Fill

1.3.0

Add @exclude rules for https://*.youtube.com/embed/* and https://music.youtube.com/*.

Add metadata: @homepageURL, @supportURL, and @icon.

Keep fullscreen-only header cover behavior (activates on fullscreenchange, deactivates on exit).

Stateless: no menu, no localStorage persistence.

1.2.0

Remove menu toggle and localStorage. Behavior is now automatic and stateless.

Auto-cover header only while in fullscreen to avoid stray black bars; revert on exit.

Listen to fullscreenchange (plus webkit/moz/MS variants) for broader compatibility.

1.1.0

Add an optional Tampermonkey menu command to toggle the header cover.

Persist header cover preference to localStorage (ytf-cover-enabled).

Minor internal cleanup and consistent version log messages.

1.0.0

Initial release.

Auto-enable Theater mode on watch pages and resize the player to fill the viewport height.

Support both ytd-watch-flexy and ytd-watch-grid; remove ambient cinematics that interfere with sizing.

Robust SPA awareness: re-apply on YouTube navigation events and after a short delay.

Calculate header offset and scroll-to-top to keep the player fully visible.

Included header cover CSS and an internal toggleCover() helper (default off, no UI exposed in this version).