gistfile1.phtml

<?php

// IF you want it to include the days, follow the logic.
$time = "1:66";
$timeArray = explode($time, ":");

if (count($timeArray) == 3) { // there is something like "5:12:23";
  $seconds = ($timeArray[0] * 60 * 60) + ($timeArray[1] * 60) + $timeArray[2];
} elseif(count($timeArray) == 2) { // there is something like "15:60";
  $seconds = ($timeArray[0] * 60) + $timeArray[1];
} else { // There is no ':" - or there is more than 3
  $seconds = $time;
}
$finalTime = gmdate("H:i:s", $seconds);

?>