/usr/share/doc/xmms2-plugin-avcodec/changelog.Debian.gz is in xmms2-plugin-avcodec 0.8+dfsg-18.1build3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/xmms2-plugin-avcodec/../xmms2-core/changelog.Debian.gz