While it's entertaining it's hard to imagine why someone would actually buy it. It's been demonstrated many times over that weight isn't a big factor in gas mileage, and with a trailer that long one would still want a vehicle with a good sized wheelbase to tow it.
One might speculate that it's well made and really nice inside (there are zero pictures of the inside, and it's not in the video either), but there are many others that are well made and nice inside and cost an order of magnitude less.
Now if they could make it for 40-50K with very good quality they might have something.