Hark! What light beyond yon window breaks?
That sure looks like a Viburnum nudum clone, of which 'Winterthur' is one and there are quite a few more commonly in commerce (not to mention arboretum collections).
I don't know how far north Possumhaw Viburnum is grown reliably. I've been to Hidden Lake Gardens all of once - back in December 1992 - and it was pretty frigid then, a crisp blue sky snow on the ground great for taking conifer pictures weather.
Possumhaw Viburnum has very glossy smooth green leaves. The pictured plant doesn't seem to boast that feature. A very similar Viburnum is Viburnum cassinoides, and it also sets such fruit that go through the color spectrum on the way to maturing blue to black. It is more common in northerly climes. Morton Arboretum outside of Chicago has a fine collection, and the former Klehm growing concerns (Beaver Creek Nursery, Song Sparrow Nursery) had named a handful of clones that performed well in the upper Midwestern states. I grew the Alphabet Group: 'Buccaneer', 'Challenger', 'Defender', 'Endeavor', and 'Freedom'.
Overall, Viburnum nudum has outperformed all the Viburnum cassinoides here, being more tolerant of summer heat/drought - even though both species prefer wetter conditions than the Valley can generally offer.
