It's amazing watching this how quickly the volunteers needed help after trying to swim to shore that was only 100 feet away. The volunteers without a lifejacket couldn't do it and would have drowned if help wasn't so close.
It's interesting watching it. The instructor on the video talks about how there is a perception that hypothermia kills most people in cold water. That isn't true as most people are long dead before hypothermia has a chance to set in. The key message out of it is that in cold water, you have a significantly higher chance of survival with a PFD on.