adding ROS World video. cannot get groot to display nicely site-by-site

when included manually it always has a wired offset to the top respective to the iframe.. but there is no such margin defined through a css in either of the objects.. unwanted to throw out groot but I have no nice solution currently.. displaying always underneath of each other isn't that nice..

Author: gramss

tutorials/docs/groot.rst

@@ -9,7 +9,17 @@ Groot - The fancy BehaviorTree Editor
 Overview
 ========
 
- .. image:: images/Groot/groot_start_menu.png
+ .. raw:: html
+
+    <h1 align="center">
+      <div>
+        <div style="position: relative; padding-bottom: 0%; overflow: hidden; max-width: 100%; height: auto;">
+          <iframe width="560" height="315" src="https://www.youtube-nocookie.com/embed/Z6xCat0zaWU?autoplay=1&mute=1" frameborder="0" allowfullscreen></iframe>
+        </div>
+      </div>
+    </h1>
+
+
 
 `Groot <https://github.com/BehaviorTree/Groot>`_ is the companion application of 
 `BehaviorTree.CPP <https://github.com/BehaviorTree/BehaviorTree.CPP>`_ to create, edit, and monitor behavior trees.