add compressed gif

build/frontpage.html

 <link href="_static/frontpage.css" rel="stylesheet">
-
-<iframe src="_images/frontpage/silence.mp3" allow="autoplay" id="audio" style="display:none"></iframe>
-
 <div class = "mdl-grid header">
   <div class = "mdl-cell mdl-cell--4-col">
     <img src="_images/frontpage/front.jpg" class="img-fluid" alt="">
@@ -55,9 +52,7 @@
     </div>
   </div>
   <div class = "mdl-cell mdl-cell--7-col">
-    <video width="410" height="300" playsinline autoplay muted loop>
-      <source src="./_images/frontpage/notebook.mp4" type="video/mp4">
-    </video>
+    <img src="_images/frontpage/notebook.gif">
   </div>
 </div>
 
@@ -78,9 +73,7 @@
 
 <div class = "features mdl-grid">
   <div class = "mdl-cell mdl-cell--7-col">
-    <video width="410" height="300" playsinline autoplay muted loop>
-      <source src="./_images/frontpage/forum.mp4" type="video/mp4">
-    </video>
+    <img src="_images/frontpage/forum.gif">
   </div>
   <div class = "mdl-cell mdl-cell--5-col mdl-cell--middle">
     <div class="content">