OK, judging by the video, one could conclude that the process isn't really complicated.
This now-ancient report on some of the first multi-colour camo fabrics with different patterns on both sides probably gives a better sense for how complicated this stuff was back then.
It has only become more complicated with extra ingredients for camouflage against night vision devices, insect repellents, water repellents and even attempts to make the fabric less permeable to chemical agents.
Too bad; almost all of the Western textile industrial capacity went overseas during the 80's and 90's (if I remember the time frame correctly). I suppose enough is left to equip a few million persons within months, though.
Back to the old patterns; the report shows why camo patterns especially for reversible clothing and tents weren't common until WW2: It was simply beyond technological reach until the late 20's. There were multi-colour camo patterns of questionable effectiveness during the First World War, but such fabrics only appeared half-way between the World Wars. Few armies substituted properly with camo nets, though; camouflage is a usual suspect for neglect during peacetime.