In short, DVD movies are encrypted by the movie-makers such that special software is required to decipher them. Older copies of Microsoft Windows® were automatically able to decipher the movies because Microsoft automatically included the software with the operating system licenses. Windows® 8, and 10, and current releases of Linux do not natively have the software necessary to decipher the movies. What is more, there are now laws that forbid programmers from writing software to decipher or crack the cryptography. Such software does exist, and its use has not yet been challenged in U.S. courts, but nonetheless, is technically illegal. Cracking encryption is now deemed similar to breaking a lock on a car or house. the end-purpose of the laws being to prevent duplication of the DVDs. (One must be aware that purchase of a DVD movie is not purchase of the entire movie itself, but only a limited license to view the movie on that particular DVD.)
Solutions include:
- Buy software that specifically licenses the right to decipher the encryption (around $20);
- Use an external DVD or DVD/Blu-ray combo player (which again has been specifically licensed by the manufacturer to decipher the encryption);
- Downgrade to Windows® 7 or prior versions (works for most older movie releases, but may fail going forward with newer releases);
- A few other odd-ball solutions exist that cannot be recommended with integrity by this author, and can be quite technically difficult to accomplish.
Reference these articles:
http://www.dummies.com/computers/operating-systems/windows-8/how-to-play-dvds-in-windows-8/
https://www.cnet.com/how-to/how-to-watch-dvds-for-free-in-windows-10/
https://help.ubuntu.com/stable/ubuntu-help/video-dvd-restricted.html
