To me it sounds like the first time he says... "why... " then.. "it's always there... I know it well".... but I think he changes it sometimes. Other times it sound's like he's saying instead of "why" its "So I" and "it was always there"...
And Stapp is singing..."now im forced to look behind, forced to look at you, you wear a thousand faces, tell me which is you - broken mirrors paint the floor but still reflect the truth - ..thousand faces...
So mark singing seems like a play on how stapp cant find his face, because it was always there and he should know it... i guess