Fix class

wagtailvideos/templates/wagtailvideos/multiple/edit_form.html

@@ -15,7 +15,7 @@
         </li>
     </ul>
 </form>
-<div data-video-thumb="{{ video.id }}" class='thumb icon icon-image hasthumb'>
+<div data-video-thumb="{{ video.id }}" class='thumb icon icon-media hasthumb'>
     {% if video.thumbnail %}
 	<img src="{{ video.thumbnail.url }}" />
     {% endif %}