Codecs for playing non-free formats are not included in Kubuntu by default. You can get support for the extra codecs by installing the libxine-extracodecs package from the Multiverse repository (see the section called “Managing Repositories”).
Some of these packages may not be permitted in some countries: you should verify that you are permitted to use them before installing them.
Due to patent and copyright restrictions, some codecs are not included at all in Kubuntu. For more information on these, go to https://help.ubuntu.com/community/RestrictedFormats.