Examine source code of Youtube AdSkip

{
  "manifest_version": 2,
  "name": "YoutubeAdSkip",
  "version": "1.1",
  "description": "Salta automaticamente los anuncios de YouTube",
  "icons": {
    "48": "ytdadskip.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.youtube.com/*"
      ],
      "js": [
        "ytdadskip.js"
      ]
    }
  ],
  "applications": {
    "gecko": {
      "id": "marotoatance@gmail.com"
    }
  }
}