ZLR - Dual Subtitles by Nera

ZLR provides real-time dual subtitles for YouTube videos with instant translation.

✨ Features:
- Dual Subtitles - See original and translated subtitles simultaneously
- Ultra-Fast Translation - Real-time with minimal delay
- Google Translate (Free) or DeepL (API key required)
- Beautiful glassmorphism overlay design
- Draggable subtitle box
- Keyboard shortcuts: A (back), S (replay), D (forward)
- 10+ languages supported

Perfect for language learners!

------------ "Update 2.2.7" ------------

🚀 New Features & Improvements

DeepL Pro Support: Added full support for DeepL Pro API keys! The extension now automatically routes your requests to the correct endpoint (Free or Pro) depending on the key you provide.
Smarter Caption Detection: The extension no longer blindly picks the first available subtitle. It now accurately hooks into the specific caption track you have manually selected in the YouTube player.
Intelligent Cache Eviction: Rebuilt the translation memory to strictly enforce storage quotas. If the storage limit is reached, it will smartly delete only the oldest 25% of cached translations rather than dropping the entire cache, saving your API limits.
Enhanced Keyboard Controls: Improved the jump-back behavior. You can now reliably use both the 'A' and 'S' keys to cleanly skip back 2 seconds, without risking negative playback time errors at the start of a video.


🛠️ Performance & Stability Fixes

Bulletproof Video Transitions (SPA): Completely rebuilt the internal observer logic to smoothly handle YouTube's dynamic page navigation. Subtitles from previous videos will no longer linger on the screen when clicking a new video.
Background Stability: Resolved "Extension context invalidated" errors. The extension no longer breaks or loses connection when the browser puts background processes to sleep.
Hash Collision Fixes: Greatly reduced the chance of translation mix-ups on very similar sentences by utilizing a more robust, content-aware 12-character hashing system.
Memory Optimization: Cleaned up aggressive loop issues and old DOM bindings that caused severe memory leaks during extended watch sessions.


🛡️ Security & Privacy

Storage Security: Your DeepL API key is now strictly saved to your browser's local, non-synced storage to ensure maximum privacy across your devices.
Permissions Cleanup: Removed unused permissions (activeTab, scripting) for a safer, lighter extension footprint that complies with the strictest Mozilla Add-ons (AMO) privacy policies.


⚠️ Known Issues

Auto-Generated Captions: The extension works best with manually uploaded subtitles. You may still experience synchronization issues on older videos or when using YouTube's auto-generated captions.
Minor Glitches on Long Sessions: After watching 6-7 videos continuously without a single page refresh, you might occasionally experience minor subtitle ghosting. A quick page refresh (F5) will resolve this instantly.


Note: We are aware of these remaining edge cases and are actively working on them. Thank you for your continued support!