I have been on the German autobahns, so I recognise what happened. At first I was surprised he had only managed to get to a Rastplaz and not to somewhere with a charger, but then I remembered a drive between (I think) Frankfurt and Würzburg, where I got very nervous in a Golf with a 50-litre petrol tank!
This is quite similar to what happened to the guy in the other videos, who thought he had enough range but was then caught out by a precipitate drop being reported by the car. A long hill could be an explanation, of course, but this seems to have been a very sudden drop.
As far as I can see, the MG4 doesn't behave like this. I regularly drive from my home to Glasgow, which involves a drop of 230 metres. I use 25% of battery to get there. I use about 28% of battery to get back. The situation is similar when I return from Edinburgh, which is a similar change in elevation but over a smaller distance. I am aware that my miles/KWh is a poorer on the way back than on the way there, but I have never experienced a sudden drop in range like that, even going up from near sea level to 300 metres in a few km.
Speed will also run the battery down more quickly of course. When my battery was on 5% I accelerated to overtake another car and went up to 80 mph (130 km/h), but the battery % didn't do anything alarming at all. (I was also going uphill when I did that, from 220 to 270 metres.)
It may be that the gradients in Germany are more pronounced and/or more prolonged, but on a motorway I wouldn't expect the gradient you'd get on a mountain road. The behavior of the car that you describe in the video, and indeed the similar behaviour of the Kia in the other videos, is quite deceptive. I have some sympathy for a driver who is caught out by this. It's quite different from the buffer of 8-15 miles (albeit sometimes at turtle speed) that's being shown for other cars (including the MG4) in other videos. (Although I think I saw a reference to a different MG model stopping not long after it got to zero range, so they may not all be the same.)
I had another look at the first Mr EV video, and he says that the battery percentage was at 20%, then it suddenly went down to 4%. I don't know how sudden that was, as I don't think the % charge is on the main screen of that car, you have to call it up specifically, so he probably wasn't watching it continuously. Nevertheless that is a very sudden drop by any standards.
He was on the motorway, but he said nothing about hills, and it would take one hell of a hill in the English midlands to drop a battery that fast. Something not right there.
Something I did think about was balancing the battery. I'm having trouble finding out for sure if that Kia has an LFP battery, but I think it does. One of the reasons (perhaps the main reason?) they tell us to charge the LFP battery to 100% and let it balance every time is that if you don't, the GOM is unreliable. The battery has a very level charging profile, or something like that, and the BMS can't really tell how much is left in a partially charged battery. It relies on knowing where it was when it was 100% charged.
I read somewhere else that it was possible for a battery that hasn't been allowed to balance to be quite hazy about how much charge it still has as it gradually gets lower, then suddenly as the end approaches it gets a real sense of where it's at and reports the truth. Hence the GOM may seem to drop very suddenly at that point.
I also have the LFP battery, but mine behaved fine when I ran it down to 4%. The projected range stayed reasonable, within kicking distance of 2 miles for every 1% charge, and there were no nasty surprises on the final leg, even when I gunned it a bit. At Abington it told me (I think) that I had 28 miles range, at 15% charge, and the distance home is 23 miles. That's where I turn off the motorway, so it's not unexpected that I got better economy after that - I was on an A road driving 40-60 mph most of the time. I saw both the range and the % charge drop evenly and predictably, and got home on 4% charge with 8 miles on the GOM.
I always take the battery to 100% and let it balance. I wonder if Mr EV had been doing a lot of partial charges on his Niro? That might explain the problem.