Nic,
The issue shown in page 3 of this thread has been experienced with Media Classic Player Home Cinema (version to date), with the MPC-HC internal video decoder enabled which is supposed to use the hardware acceleration to decode videos, when possible. This can be configured when installing the software.
I suppose that the artifacts cannot be seen if the video is not hardware decoded. I do not have other VC-1 videos so I cannot tell if this is an issue specific to this kind of video, but the VC-1 WinSAT video is not properly rendered under the above mentioned settings.
The other WinSAT videos might flicker or glitch so I would suggest trying them all so you can see by yourself.
Regards, Lio.