Windows 8 and 10 don't ship with a DVD player application, you need to install one. Until you install a DVD player application Windows will simply show you the folders on the disk which are "AUDIO_TS" and "VIDEO_TS".
There are many chargeable DVD media player applications available and several free alternatively.
Without any implied warranty, one of the free Media Players available for Windows is VLC Media Player - it can be downloaded from the following webpage:
At the time of writing, VLC Media Player supports Windows XP SP2, 2003 SP2, Vista SP1, 2008 SP1, 7 and 8.
Other free players are also available, including: