It uses TCP/IP to communicate between the recording service and GBPVR.exe/PVRX2.exe on the local machine, which triggers some firewalls.
You can also get network activity with the following:
- using client PCs.
- using client MVPs.
- using net radio
- doing the EPG update
- using plugins that get info from the web (for example, weather plugin)
If you check your firewall to see where it's going, it'll give you a clue which of these activities it is. There is nothing that talks home aka spyware.