It's a single variable vane turbo if I remember correctly.
I did watch the vids again, this time bluetoohed to my surround sound, and you're right, it sounds like both test drivers are shifting really early in the rev range. In fact, it sounds to me like they're lugging the s#@*t out of those engines for the most part. Could explain it.
Well, headlights aside, it's a gorgeous machine, and I'm sure it will perform its little head off!
PS: looks like Porsche just updated their home page to include the 718 Box front and center.