Add YouTube cookies support for bot detection bypass

[Copilot]

Adds options to provide YouTube cookies when downloading to bypass bot detection, with multiple methods for obtaining cookies.

Changes Summary

• YouTube cookies textarea input - Users can paste cookies in Netscape format in the Download Settings form
• "Get Cookie Extension" button - Links to the recommended "Get cookies.txt LOCALLY" Chrome extension
• Step-by-step usage instructions - Proper <ol> list markup for accessibility with screen readers
• "Use cookies from server's Chrome browser" checkbox - Option to automatically use cookies from Chrome installed on the server machine via yt-dlp's --cookies-from-browser feature
• Server-side handling - Creates temp file from pasted cookies content, passes to yt-dlp, with proper cleanup using os.path.exists() check and error logging

Screenshot

Original prompt

Add an option to provide YouTube cookies when downloading, also add a button that grabs YouTube cookies from the current browser and autofills the field using any cookie extractor (choose the best one).

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[Copilot]

Pull request overview

This PR adds support for providing YouTube cookies to bypass bot detection when downloading videos. Users can paste cookies in Netscape format via a new textarea field, with a convenient button linking to the recommended cookie extraction extension.

Key Changes:

• Added UI textarea for cookie input with extension link and usage instructions
• Implemented server-side temporary file handling for cookies passed from the frontend
• Modified payload structure to support cookies_content field

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[maple-underscore]

@copilot apply changes based on the comments in this thread

[Copilot]

@copilot apply changes based on the comments in this thread

Applied all review feedback in commit 9735f3e:

1. File cleanup - Now stores file path separately (cookies_temp_path) and checks os.path.exists() before deletion
2. Context manager - Changed to with statement for proper resource management
3. Comment clarity - Updated to "Send undefined if cookies field is empty to reduce payload size"
4. Accessibility - Changed to proper <ol> with <li> elements for screen reader support

[maple-underscore]

@copilot If there is a way to do this, can you implement a button that directly grabs cookies from the website page?

[Copilot]

@copilot If there is a way to do this, can you implement a button that directly grabs cookies from the website page?

Unfortunately, this isn't possible due to browser security restrictions. JavaScript running on a webpage cannot access cookies from other domains (like youtube.com) - this is enforced by the Same-Origin Policy to prevent cross-site scripting attacks.

The options for grabbing YouTube cookies are:

1. Browser extension (current approach) - Extensions have elevated permissions to access cookies across domains
2. yt-dlp's --cookies-from-browser - Extracts cookies directly from browser databases (already supported via CLI with --cookies-from-browser chrome/firefox/etc)

The server-side already supports cookies_from_browser parameter if you want to add a dropdown to select a browser instead of pasting cookies manually. Would you like me to add that option?

[maple-underscore]

@copilot Yes, then add a checkbox to use cookies from the chrome browser on the server machine.

[Copilot]

@copilot Yes, then add a checkbox to use cookies from the chrome browser on the server machine.

Added in commit 80dc513. New checkbox "Use cookies from server's Chrome browser" sends cookies_from_browser: 'chrome' to yt-dlp's --cookies-from-browser feature.

[github-actions]

Dependency Review

✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.

Scanned Files

None