Examine source code of Video Shenanigans

{
  "name": "Video Shenanigans",
  "version": "1.1.0",
  "description": "Control video with mouse clicks/taps instead of dragging seekbar. Useful on mobile devices. Double tap on the right side of video to go forward by 10 seconds and on the left side of video to seek 10 seconds back. The more quick taps you can do, the greater the seek distance.",
  "manifest_version": 2,
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "script.js"
      ],
      "all_frames": true,
      "run_at": "document_idle"
    }
  ],
  "icons": {
    "128": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{a9adbda3-09fd-4497-bf7e-055c28ecf7bb}"
    }
  }
}