How to instantly send audio from iTunes (or other Mac player) to wi-fi router and make it available to other network's devices by using ip:port?
Is it way to make it with video?
iTunes can stream audio to any AirPort Express, Apple TV, or third party AirPlay-compatible speakers. It can also stream video to Apple TV.
For streaming audio from other apps, see Rogue Amoeba's "Airfoil" product line.