Examine source code of SanShorts

{
  "manifest_version": 2,
  "name": "SanShorts",
  "version": "1.0",
  "description": "Prevents shorts from appearing in video feed grids on youtube.",
  "icons": {
    "48": "icons/sanShorts.svg"
  },
  "content_scripts": [
    {
      "matches": [
        "*://www.youtube.com/*"
      ],
      "js": [
        "sanShorts.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{fa8da144-feed-45ee-9935-fb885c7e2326}"
    }
  }
}