Examine source code of HTML5 Video Player for Facebook

{
  "name": "HTML5 Video Player",
  "short_name": "FB HTML Video",
  "version": "1.3",
  "manifest_version": 2,
  "description": "This extension will allow the user to view Facebook Videos via HTML5 Player + added functionality of downloading .mp4 video.",
  "icons": {
    "128": "images/icon-128.png"
  },
  "browser_action": {
    "default_icon": {
      "16": "images/icon-16.png"
    },
    "default_title": "HTML5 Video Player for Facebook"
  },
  "default_locale": "en",
  "permissions": [
    "http://*/*",
    "https://*/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "http://*/*",
        "https://*/*"
      ],
      "js": [
        "scripts/jquery-3.1.1.min.js",
        "scripts/contentscript.js"
      ],
      "css": [
        "styles/style.css"
      ],
      "run_at": "document_end",
      "all_frames": false
    }
  ],
  "web_accessible_resources": [
    "images/dl-btn.png",
    "video.html"
  ]
}