diff --git a/templates/html/chapter.html b/templates/html/chapter.html
index 7dafed6..969f08f 100644
--- a/templates/html/chapter.html
+++ b/templates/html/chapter.html
@@ -1,6 +1,6 @@
 <div style="float: right;">
   <div class="btn-group" role="group">
-    {% if chapter.video_url %}
+    {% if chapter["video_url"] %}
       <a class="btn btn-secondary" href="{{ chapter["video_url"] }}" target="_blank"><svg xmlns="http://www.w3.org/2000/svg" height="24px" viewBox="0 0 24 24" width="24px" fill="#000000"><path d="M0 0h24v24H0V0z" fill="none"></path><path d="M21 3H3c-1.11 0-2 .89-2 2v12c0 1.1.89 2 2 2h5v2h8v-2h5c1.1 0 1.99-.9 1.99-2L23 5c0-1.11-.9-2-2-2zm0 14H3V5h18v12zm-5-6l-7 4V7z"></path></svg></a>
     {% endif %}
     <a class="btn btn-secondary" href="{{ edition }}_slide_{{ chapter["ident"] }}.html"><svg xmlns="http://www.w3.org/2000/svg" height="24" viewBox="0 -960 960 960" width="24"><path d="M840-120v-640H120v320H40v-320q0-33 23.5-56.5T120-840h720q33 0 56.5 23.5T920-760v560q0 33-23.5 56.5T840-120ZM360-400q-66 0-113-47t-47-113q0-66 47-113t113-47q66 0 113 47t47 113q0 66-47 113t-113 47Zm0-80q33 0 56.5-23.5T440-560q0-33-23.5-56.5T360-640q-33 0-56.5 23.5T280-560q0 33 23.5 56.5T360-480ZM40-80v-112q0-34 17.5-62.5T104-298q62-31 126-46.5T360-360q66 0 130 15.5T616-298q29 15 46.5 43.5T680-192v112H40Zm80-80h480v-32q0-11-5.5-20T580-226q-54-27-109-40.5T360-280q-56 0-111 13.5T140-226q-9 5-14.5 14t-5.5 20v32Zm240-400Zm0 400Z"/></svg></a>
diff --git a/templates/html/section.html b/templates/html/section.html
index 99436de..82d0504 100644
--- a/templates/html/section.html
+++ b/templates/html/section.html
@@ -1,6 +1,6 @@
 <div style="float: right;">
   <div class="btn-group" role="group">
-    {% if section.video_url %}
+    {% if section["video_url"] %}
       <a class="btn btn-secondary" href="{{ section["video_url"] }}" target="_blank"><svg xmlns="http://www.w3.org/2000/svg" height="24px" viewBox="0 0 24 24" width="24px" fill="#000000"><path d="M0 0h24v24H0V0z" fill="none"></path><path d="M21 3H3c-1.11 0-2 .89-2 2v12c0 1.1.89 2 2 2h5v2h8v-2h5c1.1 0 1.99-.9 1.99-2L23 5c0-1.11-.9-2-2-2zm0 14H3V5h18v12zm-5-6l-7 4V7z"></path></svg></a>
     {% endif %}
     <a class="btn btn-secondary" href="{{ edition }}_slide_{{ chapter["ident"] }}.html#{{ section_id }}"><svg xmlns="http://www.w3.org/2000/svg" height="24" viewBox="0 -960 960 960" width="24"><path d="M840-120v-640H120v320H40v-320q0-33 23.5-56.5T120-840h720q33 0 56.5 23.5T920-760v560q0 33-23.5 56.5T840-120ZM360-400q-66 0-113-47t-47-113q0-66 47-113t113-47q66 0 113 47t47 113q0 66-47 113t-113 47Zm0-80q33 0 56.5-23.5T440-560q0-33-23.5-56.5T360-640q-33 0-56.5 23.5T280-560q0 33 23.5 56.5T360-480ZM40-80v-112q0-34 17.5-62.5T104-298q62-31 126-46.5T360-360q66 0 130 15.5T616-298q29 15 46.5 43.5T680-192v112H40Zm80-80h480v-32q0-11-5.5-20T580-226q-54-27-109-40.5T360-280q-56 0-111 13.5T140-226q-9 5-14.5 14t-5.5 20v32Zm240-400Zm0 400Z"/></svg></a>