Examine source code of Youtube auto play/pause

{
  "manifest_version": 2,
  "name": "Youtube auto pause",
  "version": "1.0.1",
  "description": "Use this when following a tutorial, where you are writing along. Use the shortcuts on your system to switch back and forth between youtube and whatever",
  "content_scripts": [
    {
      "matches": [
        "https://www.youtube.com/watch*"
      ],
      "js": [
        "index.js"
      ]
    }
  ]
}