User blog comment:Gardimuer/BioShock Infinite Demo & Screenshots/@comment-3042051-20100924025352/@comment-1330314-20100924173738

A setpiece moment is usually scripted. I think what the devs wanted to say there is that they used the weather system as a support for the tower collapsing, rather than its direct creation. Imagine if the bell hadn't landed at the player's feet, and instead crashed into one of the buildings. That'd mean they would have to have integrated some sort of environmental destruction system to stop it from bouncing off the walls.