When using GoVideo Enterprise for Outlook, the add-in interface displays the groups to which you belong as "folders".
You are not able to create a sub-folder underneath the GoVideo group folder to better organize your videos.
However, by using a naming system to categorize your videos (e.g. include "Team Meeting" or "Holiday Schedule Discussion" in the title of a video), you will then be able to use the provided search bar to quickly find all players within a "folder" relative to its naming convention.
So rather than create a team meeting folder, simply name the videos to include "Team Meeting", for example, thereby allowing you search your entire library to pull up all the videos with "team meeting" in the name.
For more information on how to rename GoVideo videos, please see How do I change the title of my GoVideo recordings?