Examine source code of YouTube Hotkey Blocker

{
  "manifest_version": 2,
  "name": "YouTube Hotkey Blocker",
  "version": "1.0",
  "description": "Blocks Ctrl/Alt+→/← at YouTube",
  "author": "koanvi",
  "applications": {
    "gecko": {
      "id": "yt-hotkey-blocker@koanvi.local",
      "strict_min_version": "78.0"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "*://www.youtube.com/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_start"
    }
  ]
}