VirtualBox requires an extension pack to provide support for Remote Desktop Protocol, USB 2.0, PXE booting for Intel network cards, etc. This PUEL-licensed extension pack is free for personal use.
This package downloads the extension pack from internet during install.
While the features and software may be great, the licensing model is a straight up shakedown. If you run a corporate network and your users install this, expect a large bill from Oracle. This should be removed from the repos as it is a risk.