Think about the installation of a Virtual Machine in one of your Windows Server 2008 R2 / 2012 Hosts. The mouse is not being captured, you could only copy and paste text from the Host to the Virtual machine (via the drop down of the vmconnect window, not directly).
To come around things like that, one option was to use a Remote Desktop Connection. But this only works after finishing the initial installation of the VM and not with all Client Operating Systems.
In Windows Server 2012 R2 and Windows 8.1 Hyper-V, Microsoft implemented something new:
Enhanced VM Interaction
Enhanced VM Interaction is based on the Remote Desktop Protocol and allows you to use a lot of features, even if the Client Operating System is not yet installed or if the Virtual Machine has no network connectivity:
- Smart Card, Folder, Disk and USB redirection
- Audio redirection
- Copy and Paste of files and folders (in both directions [VM<=>Host])
Note that the redirection is session based. Therefore it can’t be used for licensing dongles, etc..
Enhanced VM Interaction can be enabled for each Hyper-V Host in the Hyper-V Manager. By default it is disabled in Windows Server 2012 R2 and enabled in Windows 8.1.