The waterproofing isn't part of the 'warbow', that's just something extra he likes to do to his bows. You can see another regular Korean bow he's lacquered in this video and you can see a standard 'warbow' here with no silk/lacquer and just birch bark.
The warbow they sell isn't authentic and is a bit of a sham. It should be more reflexed, have a pronounced kasan ridge and have an almost Manchu style string bridge.
Instead they've just made a regular Korean bow, put different tips on the siyah and put a lot less reflex on the bow. The lower reflex on the bow is why they say it's easier to maintain than a proper Korean bow. No need to heat tiller/correct it but this comes with much lower arrow speed.
So in the end what you're left with is a Korean bow that's easier to take care of but shoots slower. Also limb tips look a little different. It's all a bit disappointing really, I was excited about this bow and tried to preorder it but (fortunately) I was told all the bows they were making this year were already reserved/presold.