Examine source code of Video Snapshot

{
  "description": "Display a snapshot of a YouTube video with Cmd-Opt-S. Click anywhere to dismiss.",
  "manifest_version": 2,
  "name": "Video Snapshot",
  "version": "2.0.0",
  "homepage_url": "https://github.com/Domon/video-snapshot",
  "content_scripts": [
    {
      "matches": [
        "*://*.youtube.com/*"
      ],
      "js": [
        "video-snapshot.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{f2ac9c73-f52a-410e-89b1-e64ab10ea652}"
    }
  }
}