The fact that they're interacting with it all seems to indicate they're getting some kind of value out of the game.
Is there a choice? They are stuck in a cage bored out of their minds. It is not like they were roaming free in the wild and found the giant screen and started playing with it. I've no interest in video games - but if I am stuck in a cage and the only option is to play video games, what am I going to do? Sooner or later I'll check it out, no?
Likewise, the pigs have the same choice. If they don't like the game, they can, e.g. face in the other direction so they don't have to see it (like I do in pubs that play sport on TV). (In fact, I'd be interested to see if any pigs do this.)
Besides, pigs are social animals, and there's plenty to do in that cage --- there are other pigs to interact with.
He's saying he'd do it if it's the only thing available
Some don't want to be in a pub at all.