Yeah it’s hard to say. It should be little tiny ice crystals filling the low levels that are almost suspended. The vid did look like snow crystals…a few looked pretty large. Was the whole layer full of them like fog or did you just see them in a certain area? You can definitely get flakes out of a chimney if it’s cold enough too. I’ve seen flakes falling out of light steam fog off the river here where it’s -10° or colder. You should be able to see halos and sundogs through the diamond dust too since it’s essentially a cirrus cloud at ground level.
When you see it for real the first time you know it. I’m not saying you didn’t experience true dd here, but I can’t exactly tell from the vid.