I've seen the documentary with the MG42 gunner a couple of times. He meets with a GI and a British landing craft coxwain who were also there that morining. I have even been to Omaha beach and stood in the Mg gunners tiny bunker. He had a perfectly uninterupted view of the incoming invasion. As there were no tanks or heavy equipment on the beach due to all the Duplex Drive Shermans being launched too far out he must have been pretty confident of knocking them back into the sea and according to what I have read about Bradley's thinking at the time, they came within a hairs breadth of doing it. l think it safe to say that had all defenders been determined Germans like this one instead of Ost battalions etc. D Day may have turned out differently or at least been much more costly. Remember they were expecting 50% casualties on D Day across the 50 mile front.