Version 0.6.0 is available upstream. Please consider updating!
It seems that version 0.6.0 is available upstream, while the latest version in the Gentoo tree is 0.5.2. You think this warning is false? Read more about it here.
mkvalidator is a simple command line tool to verify Matroska and WebM files for spec conformance. It checks the various bogus or missing key elements against the EBML DocType version of the file and reports the errors/warnings in the command line.