Enable Unity 3D Support for Ubuntu 12 inside VirtualBox
When you open the "unity_support_test" file in an Ubuntu 12 desktop running inside VirtualBox you might notice that Unity 3D is NOT supported. In Ubuntu 12.10 this can cause a slow guest operating system. If the host computer has a valid graphics card you can enable Unity 3D support by installing or reinstalling VirtualBox Guest Additions manually. This video demonstrates how to determine if Unity 3D is supported and how to install VirtualBox Guest Additions manually in an Ubuntu 12 Desktop.
A viewer correctly pointed out that you should also install Dynamic Kernel Module Support(dkms). Use "sudo apt-get install dkms". Dkms allows for device drivers to be rebuilt when installing a new kernel. In this video VirtualBox Guest Additions has been added as a device driver.