Summary from Blake Morrison’s post on TechNet:
“I would like to introduce you to an exciting new feature in Windows Server 2012 R2 called VMConnect Enhanced Mode.
This feature enables high fidelity RDP sessions to VM guests over the VM bus. High fidelity implies getting audio, clipboard support, USB and other redirection in addition to enhanced graphics.
Creating high fidelity sessions to guests through TCP/IP RDP connections has always been possible, but requires a properly configured network path to the VM. The VMConnect Enhanced Mode feature allows for these high fidelity sessions when no network connectivity exists between the host and guest OS’s.”