This feature is for toggling between the default setup where all pictures and videos for each session are saved in their own subfolder under the POSM video folder or all pictures and videos for each session are stored in the root of the POSM video folder.
Below is a view of the default POSM video folder where the media is stored in subfolders.
To toggle from subfolders to all media in the video folder, go to Setup File Names and check the box for Use Old Video Path (Not Media Folder).
Go to Session Management Media Tab and check the box for Revert To Video. Then check All or each session that needs to be moved and press Move Media to Folders button to move the media out of subfolders.