Examine source code of SpeedUp

{
  "manifest_version": 3,
  "name": "SpeedUp",
  "version": "1.1",
  "browser_specific_settings": {
    "gecko": {
      "id": "cce9878742cdd8dc6e563ac0e521e97ef8305927@speed-up"
    }
  },
  "description": "Allows faster video playback on YouTube.",
  "permissions": [
    "activeTab",
    "scripting"
  ],
  "host_permissions": [
    "https://www.youtube.com/*"
  ],
  "icons": {
    "48": "speedUpIcon.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.youtube.com/watch*"
      ],
      "js": [
        "speedup.js"
      ]
    }
  ]
}