Examine source code of Twitch DVR player

{
  "content_scripts": [
    {
      "js": [
        "mux.js",
        "index.js"
      ],
      "matches": [
        "https://www.twitch.tv/*"
      ],
      "run_at": "document_idle"
    }
  ],
  "description": "Replaces the standard twitch player with a custom one that supports DVR.",
  "icons": {
    "48": "twitch-dvr@48.png",
    "128": "twitch-dvr.png"
  },
  "key": "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAsovKANfWxb0VHPr258afmXdbx1muCdZz3kEIdf0BRc9+B8k8KxcSYNjLpMuAzZnd3tq5QYzp7oQXtIbvPpH+7Io7xicvhzs+x72ii+g1cxDyIkifa1nekL/E1YhPlqjcNlAsQKtjmRufVEhdMJzQ76q8ZsfWxbkdm77Z5Zg1Cxg9FZ2ciwclao1ib2/pgMa0GvpbgJ/7vHB43ok7wmlR6uEvwOUD9HUdyr3TMRzkwU7I6f5pshjjfzlJmNM139ocgFB5BajKj6qPpc0bl1kTKEhDMdU/f81gBjFArWhF76c74VLXKTSwSS+C7FDM5nyA+l7A4xS2rSUMFpHIfLnf/QIDAQAB",
  "manifest_version": 2,
  "name": "Twitch DVR player",
  "permissions": [
    "https://*.twitch.tv/*",
    "https://*.ttvnw.net/*",
    "https://dqrpb9wgowsf5.cloudfront.net/*"
  ],
  "update_url": "https://clients2.google.com/service/update2/crx",
  "version": "1.4.13",
  "browser_specific_settings": {
    "gecko": {
      "id": "{c0879866-0de7-4d6b-b52a-f3e72419413c}"
    }
  }
}