Sorry to bump this old-ass thread (especially since it has so few views from anyone else) but I got VDMod and it wouldn’t open any of the MKVs I tried. I downloaded the CCP pack of codecs and even had a few independent ones, but still nothing. So I figured I would get some MKV editors to extract the video/audio; with one of them I could create an AVI with sound, yet when I played it there was no video because it couldn’t locate the right codec (don’t I have every codec under the sun by now?!). There are some other MKV->AVI programs that sounded good, but they weren’t free and if you opted for a free trial it enforces some ungodly limit like 1-minute output videos.
Sounds like I’m out of options but I know it can’t be so. This is too simple of a task for there to be nothing to handle it.