That Nat Geo video is really hokey. A good fit for
www.luft46.com, which is a fantasy site.
In the video, they built a model of the airplane out of plywood. They finished it like a fine piece of furniture. They didn't have engines and used a lot of stuff (fiberglass and the like) that the Germans didn't have. I don't think it "proved" anything other than the guys in the woodworking shop at Northrop can make a pretty mockup. Their data showed that the model's shape reduced detection range by about 20% (versus what wasn't stated). Even if it was 20%, that matters, but, but isn't significant. I'd bet the de Havilland Mosquito (another largely wooden aircraft) was similar.
Then they went on and on about the 229 surprising the Brits by coming in fast and at low altitude. Hello... An early jet at low attitude wouldn't have enough range to make it to England and back.
After that, the video went down the path that the Germans would have an A-bomb by (or in) '46, which is nonsense. The Germans had neither a serious research program nor the resources to develop an A-bomb in the war.
Basically, it is a fanboy piece on imaginary German wonder weapons...
I'm extremely biased against the cults of Flying Wings and/or Nazi Wonder Weapons. Not that it shows.