Personally, Cutting the deck 2 is one of the best flourishing videos I've ever seen. It's very impressive manipulating knives, it's very impressive manipulating cards, but both at the same time? That's something else.
Butterfly knives are a bit different then normal knives. A butterfly knife has those 2 handles and almost pivots. I can do a bit of butterfly knifing myself actually. Although, it is very basic.
kevin james used to do some flip stick moves with a knife and ayala does a sword manip/production act and john t sheets does some knife moves in his act too i believe...
If you were referring to a completely different type of knife manipulation (such as Balisong), I'm sure you can find what you were looking for by googling it up