From Autodesk PointA:
To enable a Drawing Explorer folder
Start Windows Explorer.
Navigate to a folder that contains AutoCAD® drawing files.
From the View menu, make sure As Web Page has a check mark next to it. If it doesn't, choose the As Web Page option from the menu.
Right-click the folder and choose Dwg Explorer from the shortcut menu.
From the View menu, choose Refresh.
Select an AutoCAD drawing (.dwg or .dwt) file to view a preview image and summary information about the file.