Fixing spelling typos in comments.

common/lib/xmodule/xmodule/js/src/video/07_video_volume_control.js

@@ -116,9 +116,9 @@ function () {
         state.videoVolumeControl.volumeSliderEl.find('a')
             .on('blur', function () {
                 // Hide the volume slider. This is done so that we can
-                // contrinue to the next (or previous) element by tabbing.
+                // continue to the next (or previous) element by tabbing.
                 // Otherwise, after next tab we would come back to the volume
-                // slider because it is the next element sisible element that
+                // slider because it is the next element visible element that
                 // we can tab to after the volume button.
                 state.videoVolumeControl.el.removeClass('open');
 

common/lib/xmodule/xmodule/js/src/video/08_video_speed_control.js

@@ -148,7 +148,7 @@ function () {
             // individual speed entries.
             state.videoSpeedControl.videoSpeedsEl.find('a.speed_link:last')
                 .on('blur', function () {
-                    // If we have reached the last speed enrty, and the focus
+                    // If we have reached the last speed entry, and the focus
                     // changes to the next element, we need to hide the speeds
                     // control drop-down.
                     state.videoSpeedControl.el.removeClass('open');