Fix thumbnail updating

wagtailvideos/static/wagtailvideos/js/video-chooser.js

 function createVideoChooser(id) {
     var chooserElement = $('#' + id + '-chooser');
-    var previewVideo = chooserElement.find('.video-thumb img');
+    var previewVideo = chooserElement.find('.preview-image img');
     var input = $('#' + id);
     var editLink = chooserElement.find('.edit-link');
 
-    $('.action-choose', chooserElement).click(function() {
+    $('.action-choose', chooserElement).click(function () {
         ModalWorkflow({
             url: window.chooserUrls.videoChooser,
             onload: VIDEO_CHOOSER_MODAL_ONLOAD_HANDLERS,
             responses: {
-                videoChosen: function(videoData) {
+                videoChosen: function (videoData) {
                     input.val(videoData.id);
                     previewVideo.attr({
                         src: videoData.preview.url,
@@ -22,7 +22,7 @@ function createVideoChooser(id) {
         });
     });
 
-    $('.action-clear', chooserElement).click(function() {
+    $('.action-clear', chooserElement).click(function () {
         input.val('');
         chooserElement.addClass('blank');
     });