Since no one else has said it, blue wood is lumber with a chemical treatment against mold, rot and insects. The wood ends up dyed blue, not sure if it's the chemicals or actually dyed for easy identification and marketing. Those of use who have watched the Holmes on Homes shows know that he strongly recommends using it everywhere in home construction, not just basements.
The purple foam comment comes from his shows where he usually uses the closed cell spray foam that serves as a vapor barrier along with having the highest R-rating per inch of any spray foam insulation. The original brand of this foam had a dark blue/purplish color.