YouTube Watched

A lightweight, highly optimized userscript that adds a clear visual overlay to YouTube thumbnails you've already watched.

✨ Key Features

• Smart Threshold Detection: Only marks videos as "WATCHED" if you've completed at least 70% of the video. Say goodbye to accidentally marking videos you only previewed for 5 seconds!
• Zero-Lag Performance: Uses a debounced MutationObserver instead of heavy background loops. It idles gracefully and uses virtually zero CPU, even when infinite-scrolling through hundreds of thumbnails.
• Modern UI Support: Fully updated to support YouTube's newest grid layout, with backward compatibility for the legacy UI.
• Seamless Integration: Features a non-blocking, click-through blue overlay that perfectly matches YouTube's modern rounded-corner aesthetics.

📥 Installation

1. Install the Tampermonkey or Greasemonkey extension for your browser.
2. Click the Install button at the top of this page.

🚀 What's New in v4.0.0?

• Added: Smart Threshold Detection (reads the red progress bar and requires 70%+ watched to trigger).
• Changed: Complete under-the-hood rewrite to support YouTube's massive new 'view-model' UI update.
• Performance: Replaced legacy interval loops with a highly efficient MutationObserver.
• Fixed: The visual overlay no longer blocks you from clicking the video underneath it.

For the complete, multi-year changelog and source code, visit the GitHub Repository.