How to properly play .mkv files?

I am having a problem while playing .mkv files. Every time I play a .mkv file, the audio can be heard but video cannot be seen. The only way to see the video if I actually right click on it or put a window in front of it and it displays one part of the video but not all.

The link of the picture above basically describes what I am saying. While I was trying to take the screenshot, the window for the screenshot disappeared and displayed part of the video. I hope someone could help me on this. Thank you!

EDIT: I was running Unity 2D when I have the problem but when I run Unity 3D, it works. So I need to make this work on 2D. Please help.

Download VLC. Does .mkvs out-of-the-box flawlessly.

i would try smplayer if i were you

if smplayer didn't work i would remove the driver like boehj said and restart. then i would install, from the same place (additional drivers), the "experimental" drivers (second one in the list - if it is there before you remove the ati drivers just click activate on it without the "remove-restart-install" part) and restart again

(that's a strange bug you got there, by the way...)

(my answer is by no means a "good" one, it is just the only one i can think of right now, sorry)

(edit : by the way, there is no need going to the classic desktop to do that, just write whatever you search for in the search part of dash and it will pop up. easier than navigating to it..)