Not sure about the seafood night but I used mine's on Wednesday night (steak night) on 4/24/13. I first went to the slots club to inquire about it to see if I first needed to obtain a voucher but was instructed to go directly to the buffet cashier. Took it to the buffet cashier and everything was all good. The total value saved was $13.99, I was delighted with the savings.
On a side note, the Main Street Station 2 for 1 buffet still requires you to go to the slot club booth first to obtain a voucher first then proceed to the buffet with the voucher. No problem and still a great deal.