Excellent shot. You can clearly see the Steeler defender trying to tie up the Seattle receiver, also known as "defensive holding", or when the pass is in the air "defensive pass interference." You can see his left arm coming up trying to hook the Seattle player's right arm. Thanks for posting it.
Too bad for you, that only the offensive penalty was called. Better luck next time.
Bull... He conveniently edited out what happened before - which was defensive pass int.