Examine source code of BigConverter - YouTube to MP3 & MP4

{
  "manifest_version": 3,
  "name": "BigConverter - YouTube to MP3 & MP4",
  "short_name": "BigConverter",
  "version": "1.0.0",
  "description": "One-click YouTube to MP3 & MP4 converter. Detects videos, shorts, and playlists on any YouTube page.",
  "author": "BigConverter",
  "homepage_url": "https://en.bigconverter.com",
  "browser_specific_settings": {
    "gecko": {
      "id": "bigconverter@en.bigconverter.com",
      "strict_min_version": "140.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    },
    "gecko_android": {
      "strict_min_version": "142.0"
    }
  },
  "icons": {
    "16": "icons/icon-16.png",
    "32": "icons/icon-32.png",
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png",
    "128": "icons/icon-128.png"
  },
  "action": {
    "default_popup": "popup/popup.html",
    "default_title": "Convert with BigConverter",
    "default_icon": {
      "16": "icons/icon-16.png",
      "32": "icons/icon-32.png",
      "48": "icons/icon-48.png"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "activeTab",
    "contextMenus",
    "storage",
    "tabs"
  ],
  "host_permissions": [
    "*://*.youtube.com/*",
    "*://youtu.be/*",
    "https://en.bigconverter.com/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://*.youtube.com/*",
        "*://youtu.be/*"
      ],
      "js": [
        "lib/youtube-url.js",
        "content/youtube.js"
      ],
      "css": [
        "content/youtube.css"
      ],
      "run_at": "document_idle"
    }
  ]
}