Examine source code of download button injector

{
  "manifest_version": 3,
  "name": "YouTube Downloader",
  "version": "2.0",
  "description": "Download YouTube videos directly with yt-dlp",
  "permissions": [
    "activeTab",
    "storage"
  ],
  "host_permissions": [
    "*://www.youtube.com/watch*",
    "*://www.youtube.com/*"
  ],
  "icons": {
    "16": "icons/icon16.png",
    "32": "icons/icon32.png",
    "48": "icons/icon48.png",
    "64": "icons/icon64.png",
    "128": "icons/icon128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{dde0c677-717b-4696-954b-59215225db74}",
      "data_collection_permissions": {
        "required": [
          "none"
        ],
        "optional": []
      }
    }
  },
  "content_scripts": [
    {
      "matches": [
        "*://www.youtube.com/watch*",
        "*://www.youtube.com/*"
      ],
      "js": [
        "content.js"
      ],
      "css": [
        "content.css"
      ],
      "run_at": "document_idle"
    }
  ]
}