Added controll for video playback speed that is saved to localstorage.

resources/views/chapter/index.blade.php

@@ -69,6 +69,7 @@
         document.querySelector('body').onload = function(){
             const playbackRate = localStorage['playback'] || 1;
             document.querySelector('video').playbackRate = playbackRate;
+            document.querySelector('#playback_range').value = playbackRate;
             value.textContent = 'x'+playbackRate;
         };