Watched the video... he's just shooting on a tripod w/ no tracking... and basic advise like "avoid light pollution", and "beware of people with head...
Brant, you were right -- something was off. I did a bit more testing this morning. I believe the errors I was getting were the result of the aperture...
Not long ago I bought a used Canon EF 400mm f/2.8L IS II in great condition off of eBay (it was pristine). For kicks, I took it outside to the street...