From what I have heard, its a fairly new arcade game that works a couple ways. First, Games cost 1.00 each. You can choose to play the game or just insert a buck and get a card dispensed. This works because Konami (the makers of Yugioh) release cards that can only be purchased this way. Some older commons and uncommons in different foil varieties. Some exceptionally rare cards that aren't available anywhere else. It hinges on Konami supporting the machines with new card releases. So its hard to say how long its a viable money making option. If you check where machines are available, you can see that its mostly in major metropolitan areas: http://www.yugioh-card.com/en/events/duelterminal_locations.html
The way that the game is actually an arcade game is that a deck can be chosen from the machine or a player can scan their decks into the game. To that end I would assume that the machine would either have to be upgraded or linked to some form of network (either high speed modem, wireless, wifi....)
Best to check the youtube to see it in action. Hope that helps. As a collector, its probably not a machine to add to the collection unless your a really big yugioh fan. If you are an operator looking to make some coin in a collector card shop, you would probably be better off using one of those card dispensing Great Sluggers and putting your own mix of Yugioh cards in it unless someone you know is just trying to unload one really cheap. Hope that helps.