This had piqued my interest; just how had DRP managed to make the 5Ds look so bad when lifting data ? So this evening the sun set at 17:53, and I tried shooting into the light at ISO 250, f/2 and 1/30s, so EV7, just as DPR had. Initially this gave over exposure, as I had anticipated, and eventually it took until 18.10, so 20 minutes later before it began to balance. Then to get the effect with the side flash, using that exposure it too until 18:18 hours, so nearly half an hour. To give you an idea of how dark this is, the first picture is processed to reflect the actual luminosity of the scene as you would actually see it; that is it's beginning to get dark. My Sekonic hand held meter would not register at all.
The second picture is a screen grab of the actual frame shot at the same EV as DPR. The third is a 50% crop after adjustment, which was lightening exposure a little and lifting shadows and increasing saturation. This was on the 5DII and I've never seen it look so horrid.
So why is this ? The lift wasn't that great, and on the R G B values the dark areas are only around mid twenties, not something that would normally make the 5DII fall apart. Well as Private pointed out, it is underexposed, probably by around three stops, but the killer is the fact that it is now so dark, and the light density is so thin: there just aren't the photons about, and it is under exposed to boot. There's not enough to record.
I don't have an Exmor sensor'd camera to hand at the moment, but I'm sure that if I did the same thing, although I wouldn't get banding I'd still get very poor tonality and noise. It's just preferring one type of crap to another.
It's a crass test of a camera. Rishi from DPR seems to follow CR now, perhaps he'd like to explain himself.