DS9 loved watching "How It's Made" videos when he was younger. They're not as amusing as "Wild Kratts" (which DD7 adores), but they are fascinating.

Both kids liked "WordGirl," but you may find it too simplistic.

I'll second "Liberty Kids," too.

DD7 loves the BBC Earth videos, and both kids go on Ted-Ed binges now and then. "Mythbusters" and "Survivorman" have also been popular here for the past couple of years.