We have a radio controlled 'analog' clock, and tried to shoot a video of it doing the DST jump. It did, but not at the top of the hour! The second hand went into rapid mode some time after 1:05 UTC and finished at about 1:10 UTC. Maybe it enabled the WWVB receiver at the top of the hour and held off the high speed hands movement until after it sync'd? -- newell N5TNL