Examine source code of Youtube Seek

{
  "manifest_version": 2,
  "name": "Youtube Seek",
  "version": "1.0",
  "description": "Allows you to seek through videos on Youtube with mouse wheel",
  "icons": {
    "48": "icons/ytseek_48.png",
    "96": "icons/ytseek_96.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.youtube.com/*"
      ],
      "js": [
        "YoutubeSeek.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{782de6f0-66ad-415d-9959-51f761929f78}"
    }
  }
}