→ Firefox menu → Add-ons and Themes → Settings (gear icon) → Check for Updates
Try the Private Window test right now. If that fails, skip to Part 4 and install yt-dlp. You will never search for a "fix" again. youtube playlist downloader firefox plugin fix
This feature automatically detects which videos from a YouTube playlist you have already downloaded and only fetches the new ones. One-Click "Sync" Button → Firefox menu → Add-ons and Themes →
YouTube sometimes serves broken code only to Firefox to break plugins. youtube playlist downloader firefox plugin fix