I don’t think that’s the type of streaming video they optimized the IP on the SoC for. It’s clever, but not really useful. And who does it help exactly? Because the implication if you’re reduced to watching on a small screen is that you’re mobile, and on 5G. So the addicted user is now paying big $ for high speed data. Like giving a gambler a new line of credit.
The real question is, who interprets "You can stream 20 hours of video on one iPhone charge" as "you should watch 20 hours of video on one iPhone charge". The metric is clearly about battery life, not watching video.