MKV is a container and it does rather depend on what is inside. In this case it's a MPEG 1 or 2 (both audio & video) file which I have never seen in a MKV container. Everything is supported and Messages may shed some light here. From the audio MPGa it seems that the video would be MPEG 1, but who knows what people do or experiment with without regard for compatible files or even if they check their work.
In general when supported formats don't play indicates a problem with the file and not the player. I may be wise to get a second opinion with another player. But on the surface (without some research), I would tend to believe that another player is going to fail playing MPEG 1 or 2 in a MKV container. Gabest's MPC would be a logical choice for this test. Another would be MPlayer, but this player is not Windows friendly, unless you have lots of time to spend.