I am not very happy with this program, out of sync and all...but can anyone explain the airfoil speakers to me? i read the manual, and watched a few videos, but does it only transmit to the other computers in your house? or mac? or can it only be macs with airfoil on it? say I was at work, could I just send audio to a fellow persons mac? or at a presentation, and wanted to send audio via big screen display mac? I don't get it.