update video links

R=r
http://go/go-review/1024048
diff --git a/doc/root.html b/doc/root.html
index c6afa74..655ac23 100644
--- a/doc/root.html
+++ b/doc/root.html
@@ -28,7 +28,7 @@
   <table width="100%">
     <tr>
       <td align=center width="100%">
-        <a href="http://www.youtube.com/FIXME"><img src="/doc/video-snap.jpg"></a>
+        <a href="http://www.youtube.com/watch?v=wwoWei-GAPo"><img src="/doc/video-snap.jpg"></a>
       </td>
     </tr>
   </table>