I don't think they mean that kinda streamer - the idea is the roku tv can tell you're watching an ad even if it's on amazon prime, apple tv, youtube, twitch, wherever, and associate the ad watching with your roku account to potentially sell that data somehow?

That way they aren't cut out of the loop by you using a different service to watch something and still have a 'cut'.

It'd make sense if they're using streamer in a different sense than I'm used to. I see that's at the bottom of the definitions Google will produce.