Hi Steve,
Actually, it was just a way to display the time code of the song played in the speaker during a videoclip. So it was not really sync (I don't know if there is a solution now like an iphone slate that can be sync... I saw many "slate" app but none of them seems to be able to send a timecode via the jack...So I don't really know)
well, it's for sync purpose...
I saw it once on a macbook...