Countdown text - dynamictext

using dynamictext (or something) I want this time to count down:

Camera mic untill 4:21 (sorry)

if are wondering what this is all about:

I would prefer M:S, but H:M:S or frames or just S would be fine. it is to give the viewer an idea how much longer they need to tolerate the awful audio. and it will add a little technical bling. people like bling :wink:

See ► How to add countdown?