Examine source code of VideoBridge

{
  "manifest_version": 2,
  "name": "VideoBridge",
  "description": "Enable you to play youtube links inside facebook",
  "version": "1.1.0",
  "author": "Santa Bogdan <bogdansanta@live.com>",
  "content_scripts": [
    {
      "run_at": "document_start",
      "matches": [
        "*://www.facebook.com/*"
      ],
      "js": [
        "jquery-3.2.1.min.js",
        "content.js"
      ]
    }
  ],
  "short_name": "MTS",
  "browser_specific_settings": {
    "gecko": {
      "id": "{fb6ba290-4286-46bb-a8a4-225d1e4fe6ce}"
    }
  }
}