>> matthew beaufort is losing strength. for the first time his head slips under the water.re seems to be no official rescue response. what would you do? what would the bystanders do? should they risk their lives for someone who might not want to be saved? >> and then all of the sudden he went under and i turned around to look and garrett was gone. >> there's somebody out there coming. >> dude in full form. >> garrett couples, the life guard with the perfect record is in the water swimming from the opposite shore. beaufort's head pops back up, but it's clear, there isn't much time. >> at that point i just freestyling as fast as i could. >> he got a long way to go. >> couples knows that when a victim goes under he has only a small window, about four minutes to save someone from drowning. >> he goes under one more time that's it. >> 50 yards left to swim and matthew beaufort goes under again. >> hey, man, come on, about half an hour >> more than that. >> but garrett couples is closing in. >> i mean, my record's perfect, and i wasn't giving up. >> 900 cops here and -- >> on the