Copyright protection is a legal term, which grants certain rights regarding publication and distribution of an original work to the author of that original work. It cannot be "removed", though the author can grant access to the work, and the copyright only lasts for a specified length of time.
Here at MyCE, we help people who have purchased copies of various types of media, and who wish to make backups as part of their fair use rights. This includes both physical media and legal downloads.
Use DVDFab (as recommended by chosenfew777) or AnyDVD to break encryption on commercial dvds or blu ray disks.
For Z41dQ8's purchased iTunes video, try Tunebite.