The micro USB port is not for syncing. It is for troubleshooting and diagnostics only. To sync to iTunes you need either WiFi or Ethernet.
See this article...
I appreciate your willingness to help lkrupp, but the micro USB can be used for syncing. The ATV was already connected to my WiFi network (that's how it downloaded the software update) prior to asking me to sync with iTunes. I found a micro USB cable from an old blackberry I had for work and so I hooked it directly to the computer via the micro USB and launched iTunes. Then took it back to the TV and it was golden. Thanks though.
the microUSB can be used for 1 thing only and thats to restore the firmware if the appletv crash
also the only devices which have the microUSB connector are the 2generation and up black apples tv's which does not support sync at all being they have no harddisk you can sync to they 100% rely on access to a shared lib of a computer running with itunes running