Can you make copies of a DVD movie when there is copyright protection?
Not legally, unless you own the copyright or have obtained a license from the copyright owner.
Copyrights means you own the rights to your work. It's your choice whether someone can make copies of it, display it for people to see, publish it, or perform it in a show. No one can do any of those things without your permission. The legal protection given to ideas, inventions, or processes that have been registered with a copyright agency.
There is a widely held, but incorrect belief that copyright does not apply when the work has been published on the internet, or that it does not apply if there is no copyright notice on something. There is also a popular myth that you cannot be sued for copyright infringement if you don't make any money on the unauthorized copies you distribute.
Generally the licensing terms that companies that will present you will have you agree that you will not make copies or modify said copies without the express permission of the copyright holder(s), under a general copyright rule. However, it will be a different case if you choose to work with software that are released under the GPL or other open-source licenses.
Often professional photographers retain the copyright to pictures they take so it is technically illegal to make your own copies. Stores like Wal-Mart sometimes adopt policies to prevent any complaints about aiding copyright infringement. Your options include trying other stores, buying copies from the original photographer, or getting the original photographer to sign a release allowing copies to be made.
A watermark is a word, or series of words, (do not copy, property of, etc) overlaid in such a way as to make reuse of a copyrighted work more difficult. A copyright notice is intended to to demonstrate ownership of a particular work, that it is protected by copyright, and when that protection began.