Made it so that keyboard also prolongs auto hiding of controls.

common/lib/xmodule/xmodule/js/spec/videoalpha/general_spec.js

@@ -104,6 +104,8 @@
                     it('parse the videos if subtitles do not exist', function () {
                         var sub = '';
 
+                        // !!
+
                         $('#example').find('.videoalpha').data('sub', '');
                         state = new window.VideoAlpha('#example');
 

common/lib/xmodule/xmodule/js/src/videoalpha/04_video_control.js

@@ -75,6 +75,7 @@ function () {
 
         if (state.videoType === 'html5') {
             state.el.on('mousemove', state.videoControl.showControls);
+            state.el.on('keydown', state.videoControl.showControls);
         }
     }
 

common/lib/xmodule/xmodule/js/src/videoalpha/09_video_caption.js

@@ -109,6 +109,7 @@ function () {
 
         if (this.videoType === 'html5') {
             this.el.on('mousemove', this.videoCaption.autoShowCaptions);
+            this.el.on('keydown', this.videoCaption.autoShowCaptions);
 
             // Moving slider on subtitles is not a mouse move,
             // but captions and controls should be showed.