Examine source code of Fast YouTube Share

{
  "manifest_version": 2,
  "name": "Fast YouTube Share",
  "version": "1.2",
  "description": "Copy YouTube video URLs by pressing S while hovering over a video thumbnail",
  "permissions": [
    "clipboardWrite",
    "*://*.youtube.com/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://*.youtube.com/*"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "youtube-url-copier@example.com"
    }
  }
}