Update check is stream present

apps/school/templates/school/livelesson_detail.html

@@ -9,7 +9,7 @@
       <div class="lesson__subtitle subtitle">{{ livelesson.title }}</div>
       <div class="lesson__content">{{ livelesson.short_description }}</div>
       <a class="lesson__video video" href="#">
-        {% if livelesson.is_online %}
+        {% if livelesson.stream_index  %}
         <iframe src="https://player.vimeo.com/video/{{ livelesson.stream_index }}" width="640" height="360" frameborder="0" webkitallowfullscreen
           mozallowfullscreen allowfullscreen>
         </iframe>