working

background.js

@@ -0,0 +1,20 @@
+// Listen for web requests
+browser.webRequest.onBeforeRequest.addListener(
+  function(details) {
+    const url = new URL(details.url);
+    
+    // Check if the URL is a YouTube URL
+    if (url.hostname === "www.youtube.com" || url.hostname === "youtube.com") {
+      // Extract the video ID from the URL
+      const videoId = url.searchParams.get("v");
+      if (videoId) {
+        // Rewrite to the embedded URL format
+        const embedUrl = `https://www.youtube.com/embed/${videoId}`;
+        return { redirectUrl: embedUrl };
+      }
+    }
+  },
+  { urls: ["<all_urls>"] },
+  ["blocking"]
+);
+

manifest.json

@@ -0,0 +1,17 @@
+{
+  "manifest_version": 2,
+  "name": "YouTube URL Rewriter",
+  "version": "1.0",
+  "description": "Rewrites YouTube URLs to embedded format.",
+  "permissions": [
+    "webRequest",
+    "webRequestBlocking",
+    "<all_urls>"
+  ],
+  "background": {
+    "scripts": ["background.js"]
+  },
+  "icons": {
+    "128": "icon.png"
+  }
+}