Start/clear a countdown or alert when firing a cue

We'd like the option to be able to specify a countdown that would begin when a cue is selected, and then have the next cue clear the countdown. Example: Preservice slide calls a Countdown to Time, and then enters a slide loop (not including the slide that started the countdown). Then, we play a 1-minute countdown video for the last minute of the countdown - so it would be nice if that cue could clear the Presenter countdown automatically so we don't have to bounce back and forth to clear the countdown and fire the video on time.