Enable JS API on Youtube Embeds

The hook in the previous example doesn't work, in Drupal 10.1 at least, because the $variables['media'] variable shouldn't be a string. It should be an IFrameMarkup object. Setting it as a string like in the previous comment causes the embed to render as plain text markup, which is visible on the page. Instead, create a new object, with the value of the replaced string.

function hook_preprocess_media_oembed_iframe(array &$variables) {
  $resource = $variables['resource'];
  if ($resource->getProvider()->getName() === 'YouTube') {
    // We are rendering a YouTube video, so modify the URL of the video so that it only shows related videos from the same channel.
    // The video's markup is only available as a string, so we need to use str_replace() to modify the URL.
     $new_string = str_replace('?feature=oembed', '?feature=oembed&enablejsapi=1', (string) $variables['media']);
     $new_media = $variables['media']::create($new_string);
     $variables['media'] = $new_media;
  }
}