Source for multimedia/kmplayer is kmplayer-0.8.4-rc4a.tar.bz2 which has been
removed by author (or actually overwritten by rc4b), which means that building
ports fail. In communication with the author he reports that it was removed
due to bugs. Furthermore, he asks FreeBSD not to point a release candidate
code without communcating with him.
Last stable code according to the home page is
Update to ports information.
Try to build the port.
Over to the maintainer.
Port has been updated and developer has been correctly informed. Thanks!