Don't preload embeds by default

app/assets/javascripts/widget.js

@@ -13,7 +13,7 @@
       }
     }
 
-    var options = ['size', 'speed', 'autoplay', 'loop', 'theme', 't'];
+    var options = ['size', 'speed', 'autoplay', 'loop', 'theme', 't', 'preload'];
 
     return '?' + options.map(format).filter(Boolean).join('&');
   }

app/presenters/bare_asciicast_page_presenter.rb

@@ -6,7 +6,8 @@ class BareAsciicastPagePresenter
     decorated_asciicast = asciicast.decorate
 
     playback_options = {
-      'theme' =>  decorated_asciicast.theme_name
+      'theme' =>  decorated_asciicast.theme_name,
+      'preload' => false
     }.merge(playback_options)
 
     new(decorated_asciicast, EmbedPlaybackOptions.new(playback_options))