Examine source code of Open Watch Party

{
  "manifest_version": 2,
  "name": "Open Watch Party",
  "description": "Free, open source, lightweight watch parties with realtime playback sync.",
  "version": "2.3.0",
  "icons": {
    "16": "/16.png",
    "24": "/24.png",
    "32": "/32.png",
    "48": "/48.png",
    "64": "/64.png",
    "128": "/128.png"
  },
  "permissions": [
    "storage",
    "tabs",
    "*://*.netflix.com/*",
    "*://*.youtube.com/*",
    "*://youtu.be/*",
    "*://*.youtube-nocookie.com/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "open-watch-party@ruszabarov.com",
      "data_collection_permissions": {
        "required": [
          "browsingActivity",
          "websiteContent"
        ]
      }
    }
  },
  "content_security_policy": "script-src 'self'; object-src 'self'; connect-src 'self' http://localhost:1999 ws://localhost:1999 http://127.0.0.1:1999 ws://127.0.0.1:1999 http://localhost:3000 ws://localhost:3000 https://* wss://*",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_title": "Open Watch Party",
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.netflix.com/*"
      ],
      "run_at": "document_start",
      "js": [
        "content-scripts/netflix-player.js"
      ],
      "world": "MAIN"
    },
    {
      "matches": [
        "*://*.netflix.com/*"
      ],
      "js": [
        "content-scripts/netflix.js"
      ]
    },
    {
      "matches": [
        "*://*.youtube-nocookie.com/*",
        "*://*.youtube.com/*",
        "*://youtu.be/*"
      ],
      "js": [
        "content-scripts/youtube.js"
      ]
    }
  ]
}