It's just the way you moe your hands. The more skilled you get the more control you have on the cards. You will tehn be able to just add a little twist and shake of the hand and it will make the flourish look better. Go on youtube and check out richard's tutorial on the one card twirl. That's what flare is.
Huron's "firefly" is just a bunch of waving your hands around while you twirl a couple cards in every way imaginable with one hand (which ends up being about 4 ways) ... So, if there is any twirl you do with a card, there is a chance that it is included in "firefly". This is why I think its dumb to give names to such simple moves. Like the thing where you do a TG deck flip with packets facing opposite ways, and one of them flips a bit extra so you end with a normal deck. Lots of people do this by accident but I'm pretty sure one of those dudes like daren or something had to give that name and claim it.