How to play an MKV 3D side-by-side video?
Solution 1:
PowerDVD 10 Ultra Mark II should be able to play 3D half-SBS MKV files. Did you try enabling 3D by clicking on the "3D button"?
I have had better luck with Stereoscopic Player when it comes to 3D MKV files. If Stereoscopic Player fails to play the file, try installing K-Lite Codec Standard Pack.
Solution 2:
Bino 3D supports playing MKV, and is free+open source:
http://bino3d.org/download.html