Examine source code of CaptionClip

{
  "manifest_version": 2,
  "name": "CaptionClip",
  "version": "1.9",
  "description": "Extract YouTube video transcripts with one click. Instantly copy closed captions/subtitles to your clipboard.",
  "permissions": [
    "clipboardWrite"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://*.youtube.com/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "icons": {
    "48": "icon.png",
    "128": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{99412d38-18f0-44d1-bbdd-f75de2c99e36}"
    }
  }
}