Yakov was probably the only person present who wasn't impatient for the feast to end. He probably only stopped eating because somebody made him. "Will you stop eating! I want them to clear everything away so we can find out who the champions are!" He wasn't remotely surprised to see Viktor chosen (and probably mumbled something along the lines of 'and I gave up dessert for this news'). Harry being chosen as the 4th champion was more surprising to him. He found it interesting rather than shocking, though. He has heard all about Harry Potter and thinks if there was going to be a fourth champion is might as well be him. He's not bothered about the unfair advantage of having two champions, because he doesn't much care who wins.