Fixes for activeViewport reactivity

Packages/viewerbase/components/viewer/playClipButton/playClipButton.js

@@ -1,7 +1,7 @@
 Template.playClipButton.helpers({
     'isPlaying': function() {
         Session.get('UpdateCINE');
-        var viewportIndex = Session.get('ActiveViewport');
+        var viewportIndex = this.activeViewport.get();
         return !!OHIF.viewer.isPlaying[viewportIndex];
     }
 });