Examine source code of Undistract YouTube

{
  "manifest_version": 2,
  "name": "Undistruct YouTube",
  "version": "1.2resigned1",
  "description": "Hides comments and related-videos section of YouTube.",
  "icons": {
    "48": "icons/48.png"
  },
  "applications": {
    "gecko": {
      "id": "undestructyoutube@bytewar"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.youtube.com/*"
      ],
      "js": [
        "app.js"
      ]
    }
  ]
}