As for the DVD question... The mint cinnamon comes boxed with a multimedia player. But before it can work you have to go to Menu/Sound and Video/Install codecs. After this it will play DVDs and the Rhythm Box will play audio CDs. I guess they make it an additional step to install the codecs so that you get the very newest codecs from the start instead of needing to be updated.
I understand that; my question was about legality. I would rather buy the Fluendo OnePlay if playing them was illegal, as it seems to be (and I wish they all used Ogg). But I do not want to spend about as much as Windows cost me just to play protected content, presuming that the Ultra DVD player from the Windows store is itself legal to use.
More research finds this: Why Watching DVDs on Linux is Illegal in the USA
And Fedora states,
Fedora is unable to include support for playback of DVD video because it requires patented technologies and the necessary software may violate the Digital Millennium Copyright Act (DMCA), a copyright law of the United States. The MPEG-2 video compression format is protected by patents under United States law and international treaties. The CSS encryption scheme is a copyright protection measure, and the code that open source players must use to decrypt DVD media [via libdvdcss] using this scheme may violate the DMCA since it can be used to circumvent that protection.
Thus nocodec' versions of the Mint iso images used to be offered.