if he's not using the oem boost soleniod, the 25DE wiring loom is also fine for the DET conversion. Done it ourselves.
prawln: Is the 25DET a S1 or S2? AFM's between DE and DET motors are exactly the same, although the pink stickered AFM you have is for a series 2, and i don't think they are interchangable with S1.
We did the same conversion in my cousin's 33. At first it was running like absolute shit. All new parts installed - plugs, FMIC, pod, turbo back exhaust, 34 NEO turbo, walbro pump, aluminium radiator, new plugs, coils etc. He was running a little higher boost (around 8psi) and the car was cutting out exactly like in yours in the video. Lowered the boost down to 5psi and the problem wasnt so bad, but it was still running rough as guts.
tried everything we could, interchanging parts from another turbo 33, checking for boost leaks, consult, you name it.
anyhow, problem solver: Z32 ECU + NISTUNE + dyno tune! no more cuts, smooth through the revs, 12psi - gained 60something rwkw! and she f**kin flies.
not saying you need to run out and buy Nistune, but still, check for the obvious - any loose plumbing, BOV recirculation, try another ECU. You'll get there mate.