Issue #310 video volume reset fix

ui/js/component/video/internal/player.jsx

@@ -52,13 +52,23 @@ class VideoPlayer extends React.PureComponent {
           once: true,
         }
       );
+
       mediaElement.addEventListener(
         "webkitfullscreenchange",
         win32FullScreenChange.bind(this)
       );
+      mediaElement.addEventListener("volumechange", () => {
+        localStorage.setItem("prefs_volume", mediaElement.volume);
+      });
+      mediaElement.volume = this.getPreferredVolume();
     }
   }
 
+  getPreferredVolume() {
+    const volumePreference = parseFloat(localStorage.getItem("prefs_volume"));
+    return isNaN(volumePreference) ? 1 : volumePreference;
+  }
+
   componentDidUpdate() {
     const { mediaType, downloadCompleted } = this.props;
     const { startedPlaying } = this.state;