In the video they use a seasoning that looks like it is more than salt (maybe salt + black pepper?). Maybe combine a big mac patty with that seasoning and you might get close to the original Quarter pounder?

That is a really good question for which the answer has so far eluded me. The texture I have pretty much nailed by adding salt into the ground beef instead of seasoning from the outside, which makes it denser, more meatloaf-like, pretty much like freezing them would.

And the warming bin effect can be faked by wrapping it in grease paper and microwaving them for ten, fifteen seconds.

Thanks for the link to the channel! I'll give some of the other videos a watch. I'm pretty sure though that German burgers have never used preservatives or fillers — the former would not have been legal and the latter because they were always steadfast that the patties were 100% plain German beef.

And the taste test with everything else removed is a good idea, too! I'll give that a shot.

Man, now I really want to make another batch. Maybe together with the beef tallow fried fries I have always wanted to try...