The technological term used to describe the process of copying data from a DVD or CD to the computer's hard disk drive is known as 'ripping'. It is possible to rip audio from a compact disc to the hard drive using Windows Media Player but unfortunately not a DVD. Luckily though, there are a number of freeware applications, that is software available for free to download off the Internet, that are able to rip movies from DVD to your computer.
One such programme of this ilk is aptly titled DVD Rip (downloadable at lifehacker.com/355281/dvd-rip-automates-one+click-dvd-rippin). This is a one touch DVD ripping application that works in conjunction with another programme called DVD Shrink (which can be downloaded at softpedia.com/progDownload/DVD-Shrink-Download-4128.html). The latter programme is also freeware and it has the power to shrink the file size of your DVD via a process known as compression. Compression will have an effect on the quality of the final output however. If that is a sacrifice you are willing to make then it will give you a lot more disk space to be able to copy other DVDs.
You are able to playback the newly ripped DVDs using Windows Media Player by simply adding them to the Windows Media Library folder. If you find that for some reason it won't play back (for instance you may not have the correct codecs installed) all is not lost as there are plenty of media players that will allow playback. Highly recommended is VLC player, which will play almost any digital video format thrown at it, and is available for free download at www.videolan.org/vlc.