Você precisa de um Windows Media Center ou de um aplicativo de terceiros como < a href="http://www.videolan.org/vlc/index.html"> VLC Media Player .
Da Wikipedia
Support for playing DVDs has been removed from Windows Media Player due to the cost of licensing the necessary decoders (especially for devices which do not include optical disc drives at all) and the prevalence of streaming services such as Netflix. For the same reasons, Windows Media Center will no longer be included by default on Windows 8 as well, but the software (which also includes support for DVD playback) can be added back through the paid "Pro Pack" (for the base version of Windows 8, which also upgrades the system to Windows 8 Pro) or "Media Center Pack" (for Windows 8 Pro) add-ons. Windows 8 will still support third-party DVD playback software