A viewer-second is the primary delivery unit: the concurrent viewers present multiplied by the seconds the creative rendered, summed moment by moment; every other delivery figure derives from it, with the live capture path still being built.
The primary delivery unit: audience integrated over render time, designed to be summed as the concurrent viewers present multiplied by the seconds the creative rendered, moment by moment. Every other delivery figure derives from it.
The model is built; the live capture path that would feed it off a running broadcast is still being built.