I've not had a ton of experience with double cone dryers, but I know that they are a common means of drying compound. They are certainly unique-looking - I presume that it took many years to come up with that shape.
McConville's "The Pilot Plant Real Book" mentions that the agitation is gentle and you get decent product homogeneity, which is good. I presume that you load up the product in one handway, turn on the vacuum (and the heat?) and allow it to slowly rotate and dry product. As the video shows, they don't rotate very fast. When you're done, you get your bag ready and open it up and let the product fall down? Dunno.
I am going to guess that cleaning one of these things is a bear, but again, not much personal experience with them.