Examine source code of Fluent Immigrant

{
  "manifest_version" : 3 ,
  "name" : "Fluent Immigrant",
  "version" : "0.2.4",
  "homepage_url" : "https://fluentimmigrant.com",
  "description" : "Learn English with dual subtitles on YouTube, Netflix and Prime Video. Click any word: meaning, audio, flashcards.",
  "icons" : {
    "16" : "icons/icon-16.png",
    "32" : "icons/icon-32.png",
    "48" : "icons/icon-48.png",
    "128" : "icons/icon-128.png"
  },
  "action" : {
    "default_title" : "Fluent Immigrant",
    "default_popup" : "popup.html",
    "default_icon" : {
      "16" : "icons/icon-16.png",
      "32" : "icons/icon-32.png",
      "48" : "icons/icon-48.png",
      "128" : "icons/icon-128.png"
    }
  },
  "permissions" : [
    "storage" ,
    "scripting" 
  ],
  "host_permissions" : [
    "https://app.fluentimmigrant.com/*" ,
    "https://app.thefluentimmigrant.com/*" ,
    "https://www.youtube.com/*" ,
    "https://www.youtube-nocookie.com/embed/*" ,
    "https://www.netflix.com/*" ,
    "https://*.primevideo.com/*" ,
    "https://www.amazon.com/gp/video/*" 
  ],
  "web_accessible_resources" : [
    {
      "resources" : [
        "icons/icon-128.png" 
      ],
      "matches" : [
        "https://www.youtube.com/*" ,
        "https://www.netflix.com/*" ,
        "https://*.primevideo.com/*" ,
        "https://www.amazon.com/*" 
      ]
    }
  ],
  "content_scripts" : [
    {
      "matches" : [
        "https://www.youtube.com/*" 
      ],
      "js" : [
        "content-yt-hook.js" 
      ],
      "run_at" : "document_start" ,
      "world" : "MAIN" 
    },
    {
      "matches" : [
        "https://www.youtube.com/*" 
      ],
      "js" : [
        "content-youtube.js" 
      ],
      "run_at" : "document_idle" 
    },
    {
      "matches" : [
        "https://www.youtube.com/embed/*" ,
        "https://www.youtube-nocookie.com/embed/*" 
      ],
      "js" : [
        "content-yt-hook.js" 
      ],
      "run_at" : "document_start" ,
      "world" : "MAIN" ,
      "all_frames" : true 
    },
    {
      "matches" : [
        "https://www.youtube.com/embed/*" ,
        "https://www.youtube-nocookie.com/embed/*" 
      ],
      "js" : [
        "content-yt-embed.js" 
      ],
      "run_at" : "document_idle" ,
      "all_frames" : true 
    },
    {
      "matches" : [
        "https://www.netflix.com/*" 
      ],
      "js" : [
        "content-nf-hook.js" 
      ],
      "run_at" : "document_start" ,
      "world" : "MAIN" 
    },
    {
      "matches" : [
        "https://www.netflix.com/*" 
      ],
      "js" : [
        "content-netflix.js" 
      ],
      "run_at" : "document_idle" 
    },
    {
      "matches" : [
        "https://*.primevideo.com/*" ,
        "https://www.amazon.com/gp/video/*" 
      ],
      "js" : [
        "content-pv-hook.js" 
      ],
      "run_at" : "document_start" ,
      "world" : "MAIN" 
    },
    {
      "matches" : [
        "https://*.primevideo.com/*" ,
        "https://www.amazon.com/gp/video/*" 
      ],
      "js" : [
        "content-prime.js" 
      ],
      "run_at" : "document_idle" 
    },
    {
      "matches" : [
        "https://app.fluentimmigrant.com/*" ,
        "https://app.thefluentimmigrant.com/*" 
      ],
      "js" : [
        "content-connect.js" 
      ],
      "run_at" : "document_start" 
    }
  ],
  "background" : {
    "scripts" : [
      "background.js" 
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "extension@thefluentimmigrant.com",
      "strict_min_version": "140.0",
      "data_collection_permissions": {
        "required": [
          "authenticationInfo",
          "websiteContent"
        ]
      }
    }
  }
}