Play mkv files
Unfortunately the link below no longer works, but the following should help http://forum.linuxmce.org/index.php?topic=11497.0
This page explains how to achieve successful playback of Mkv/H264/X264 files on Linuxmce 810 with some limitations.
The following instructions will allow playback of most types of mkv containers with VDPAU, but the instructions will break VDR.
You will have to forcefully install a backported libxine prepared by niz23. The debs they are located here: http://tschak.homelinux.com/deb/ They need to be installed all at the same time, with dpkg.
Download the .debs, place them in their own folder just to be safe (I created a folder called "MKV" in "/root/home/Desktop", which is where Firefox normally puts downloaded files), and then in a terminal...
cd /root/Desktop/MKV sudo dpkg --install libxine*.deb
For reasons I do not understand, the use of "-i" (instead of "--install") does not work - User:Purps
Note that there is no support for these packages, and they WILL break VDR.
Possible Update: When reading about this issue I stumbled across a forum post that suggested the latest linuxmce build after doing a dist-upgrade has a version of libxine that plays MKV via VDPAU like it should but also doesn't break VDR. The link is here: http://forum.linuxmce.org/index.php?topic=10013.30 I will check into this and report back.
Another method, if you see green artifacts, is to rename the files to .m2ts and changing media type to "LinuxMCE Blu-Ray". This makes LinuxMCE use mplayer to play mkv files instead of xine, however in that case you loose the ability to pause.