add instructinos for enabling local playback

options.html

@@ -62,6 +62,15 @@ <h4>The video controls are not showing up?</h4>
         <li>Disable "Adobe Flash Player"</li>
         <li>Restart your browser and try playing your video again</li>
       </ul>
+
+      <h4>The speed controls are not showing up for local videos?</h4>
+      <p>To enable playback of local media (e.g. File &gt; Open File), you need to grant additional permissions to the extension.</p>
+
+      <ul>
+        <li>In a new tab, navigate to <code>chrome://extensions</code></li>
+        <li>Find "Video Speed Controller" extension in the list and enable "Allow access to file URLs"</li>
+        <li>Open a new tab and try opening a local file, the controls should show up</li>
+      </ul>
     </div>
   </body>
 </html>