For mplayer2, I'm finding that Intel and Nouveau (but not Nvidia) need -vf format=yv12 for Hi10P to render properly with gl output on Linux. Haven't tested Windows.
Could it be a problem with Mesa/Gallium or is it on the end of mplayer2/libav?
Here's an example of output without yv12:
Thankfully, VDPAU+ffh264 is fine.