they just probably got promo vinyl or cd's that have the beat and accapella on them. They do that all the time. If you tried to remove or filter out the beat from vocals your finished product would be so muffled and manipulated you would'nt wanna use it anyway.
yeah I always wondered that cuz I be listening to dj's on the radio and they'll be playing a song and then all of a sudden the beat drops out and then its just vocals and then they throw in another beat..how they do that??? I know they are using that rave software where they can scratch with mp3's on turntables..