Amazon's internal numbers on Prime Video, revealed

>But a person familiar with its strategy said the company credits a specific show for luring someone to start or extend a Prime subscription if that program is the first one a customer streams after signing up. That metric, referenced throughout the documents, is known as a “first stream.”

That seems disingenuous as described. It would really only make sense to use that metric if that was the first prime interaction they had at all, but if they first bought a couple things and then listened to some music and only then watched a video I don't really believe that you could say they were acquired through the video.