Think of the ND filter as just a tool to A) help you achieve the 180 degree shutter angle for video OR B) if the light is SO bright even for stills that you need ND to get proper exposure.
Regarding AUTO settings, I highly encourage you to use manual settings--especially for auto white balance in video. As you circle around a subject, you may see the WB literally change / adapt before your eyes in the same take with auto WB. Even from take to take when you go to edit and many of the shots are different WB. Amateur look. Auto exposure is a slightly different matter where in some cases it *might help you, like if you are in a hurry, but most often not IMHO.