Update to final video on the homepage (#208)

* Update to final video on the homepage
* Remove video placeholder image and import

Author: microbit-grace

src/imgs/video-placeholder.png

@@ -34,7 +34,6 @@
   import StandardDialog from '../components/dialogs/StandardDialog.svelte';
   import { clearGestures } from '../script/stores/mlStore';
   import { get } from 'svelte/store';
-  import introVideoPlaceholderImage from '../imgs/video-placeholder.png';
 
   const playgroundSurveyUrl =
     'https://microbit.org/teach/playground-survey/exploring-machine-learning/';
@@ -79,28 +78,19 @@
   <h1 class="sr-only">{$t('content.index.title')}</h1>
   <div class="mb-8">
     <div class="flex flex-col items-center justify-center m-10 gap-5">
-      <!-- svelte-ignore a11y-no-noninteractive-element-interactions -->
-      <img
-        src={introVideoPlaceholderImage}
-        alt="Placeholder image for introduction video"
-        on:click={() => alert('This is just a placeholder for the final video')}
-        class="w-38rem h-auto aspect-video"
-        style="aspect-ratio: 16/9" />
-      <!-- Once we have the final video URL
-           Avoid youtube cookie. rel=0 should limit related videos to youtube channel.
+      <!-- Avoid youtube cookie. rel=0 should limit related videos to youtube channel.
            Once we have translated videos we can try e.g. cc_lang_pref=fr
            but we'll need to check our codes match theirs.
-
+      -->
       <iframe
         class="w-38rem h-auto aspect-video"
         style="aspect-ratio: 16/9"
         title={$t('homepage.introVideo')}
-        src="https://www.youtube-nocookie.com/embed/u2u7UJSRuko?rel=0&cc_load_policy=1"
+        src="https://www.youtube-nocookie.com/embed/ZhUtuuQemFc?rel=0&cc_load_policy=1"
         allow="encrypted-media"
         frameBorder="0"
         allowFullScreen>
       </iframe>
-      -->
       <p>
         <HtmlFormattedMessage
           id="content.index.toolInfo"