How can I assign a video or audio file to an existing Media Group?

Assigning a video or audio file to an existing Media Group is done through the video/audio edit page. Click on the left-hand menu "Media" and select either Video Archive or Audio Archive. Click on the video or audio file you would like to assign to a Media Group and switch to the "MEDIAGROUPS" tab. Now you can assign the video (or audio) to an existing Media Group, or you can create a new Media Group.