I haven't watched it yet, but ae they saying that their white gold is yellow gold with plating, or that tehir white gold is a bit yellow, and is then plated. The latter is normal. Stullers X1 white gold is WHITE white gold, and 19k whte gold that you can get in Europe and Canadam is WHITE white gold., The actually alloy blend makes the gold white. But generally, white gold has a warm wellow colour about it, and it is not white. When it wear, it looks warmer wear it has worn, but it would not be the same as yellow gold plated with rhodium and then that showing through.
If you don't want to deal with plating, use something like Stullers X1 or 19k white, pd, or plat.