Recording Dj Set Mac

How can a Pro DJ uses turntables to control music on a laptop?
I was in Las Vegas at a club called Lil Luna up above the palms. I saw the DJ's created. There were 2 courses a mixer and a laptop Mac. I watched him mingle through several songs. I thought he was choosing his music on the laptop because he never changed the records that were in the dishes. was able to control the speed and was able to scratch the song I chose from the laptop on the turntable?? I puzzel. What software? what player? can be done with a PC or simply a MAC?
I think you can do both. They are using the computer to select the songs and shows them all sorts of things so they can overcome party / manipulate a song very easily. They still have two plates and there are "blank records" in which to stay there overnight trip. The system can pick up the movement of such records and transform it to music, so they can still scratch and do all the things you used to do well. The difference is that they not have to change the registration for each song, the team has the songs and the registration plates are used to manipulate them. I also believe you can do with any good dish, I suggest a good / quality as it would be the handling of the thing and have a good arm on it and the needle. Anyway as for the software and things not I'm so sure, but my friend has been doing for a moment and looked at the setup is fairly easy. He said the name of the software, but I forgot. It's really great and works very well though as he would like to give it a try. No more loading stacks and stacks of records in one place, and the easiest way to manipulate the hand and add your own touch. You also do not need to be a professional if you are interested it's fun just to try it anyway. For some reason I think the software has been about $ 300, but I'm not sure, that number will only be presented as a kind of a guess.
How to Record a DJ Mix on a Mac – Hardware