It's a decent list but he listed a lot of areas that are part of different story steps. I can get that people can miss those locations if they don't play that specific story but it's a bit of a stretch to call story locations "hidden".

That pirate ship in gilded hollow looks like a goonies reference to me.

As for my favorite hidden places... I like finding the Easter eggs that the map designers put in as their way to sign the maps they made.