I recently watched the Casy (Terran) vs July (Zerg) match from 2006-2007 OSL Season 3. This was game 3 from round 1 of the elimination bracket. The game is notable for being very short and including a deception that tricks July into believing that Terran has expanded when they are actually massing units for an aggressive push.
This deception is accomplished by long distance mining their expansion while the mineral patches are in view of an Overlord (relevant part starts at 5:37):
This encourages Zerg to believe that Terran is not pushing off of one base and Zerg therefore plays somewhat less defensively than they would against 1-base aggression.
Approximately 30 seconds later, Casy moves out with his forces. July has Zerglings waiting outside of Casy's base so, they see the leading marines moving out:
Upon seeing this move out, July immediately starts a single sunken colony:
Approximately 15 seconds later, July starts a second sunken colony:
The first sunken colony completes almost exactly when the attack hits, but the second is too late to participate in the fight:
It begins morphing as the battle starts and is eliminated right as it finishes:
Why was this second sunken colony created when it was? If July perceived that it was needed, my assumption is that Zerg would have built it at the same time as the first to have it ready on time. Did July realize before the attack that this wasn't a two base play and adjust their response? I didn't see anything obvious in the video to indicate that July picked up any new information as the Terran forces moved across the map that would have revealed the deception.