Examine source code of MP4 Stream Blocker

{
  "manifest_version": 2,
  "name": "MP4 Stream Blocker",
  "version": "1.0",
  "description": "Blocks all .mp4 streams on webpages.",
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{25eedef1-9783-4096-ae61-925e87ccc0e6}"
    }
  }
}