The interesting part is the E-Core on A19 Pro are nearly as good as the previous ARM Big Core while only using half the power. I would love to know the die size of the cache and E-Core.

ARM were catching up to Apple in terms of big core, now Apple has leapfrogged in E-Core again. But competition is good. ARM should have some announcement coming in next few months.

Is there some magic with AI that lets you watch those videos dubbed in English?

There's a YouTube feature but the creator needs to enable it per-video.