Examine source code of Changelink

{
  "manifest_version": 2,
  "name": "Changelink",
  "version": "1.0",
  "description": "Changes url to something else. it maybe a redirection to mirror",
  "icons": {
    "48": "icons/link_icon_48.jpg"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.youtube.com/*"
      ],
      "js": [
        "changelink.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{5fddedfe-252b-4458-a788-88095f28e52c}"
    }
  }
}