In the video you duplicate the node group and then delete the hue node for the glossy. When i did this, the hue also disap...

Hi, Kent didn't mention that when node groups (or most things in blender for that matter) are duplicated they will share data, that is, they are linked. In the node group Kent created, the field that says 'NodeGroup' has a little button next to it. with the number 3 inside. That number will change depending on how many NodeGroups are linked together/ copied from each other. The number means that there are '3' things sharing the same info. When the nodes inside change, those changes affect the others copied/linked node groups. To break the link, click on the button, '3' in this case. Doing so will make that NodeGroup a Single User; the changes you make to it will not affect the other groups. The name will change to 'NodeGroup.000' or something similar and you can edit it without changing the other NodeGroups.

Thank you! =)