Wii U does not have DVD or Blu-ray playback capabilities.
The reason for that is that we feel that enough people already have devices that are capable of playing DVDs and Blu-ray, such that it didn't warrant the cost involved to build that functionality into the Wii U console because of the patents related to those technologies.
Makes perfect sense to me. Nintendo has always been out to create a game machine, not a home video player. Why bother with the added expense of licensing DVD and BluRay technologies when everyone should already have a device to do just that already?