The 518 build correct the issue with DXVA playback I was having, as discussed on the thread from the HTPC forum:
http://www.avsforum.com/avs-vb/showt...=972503&page=6
MeGUI encode using HD-DXVA-HQ profile, from MPEG 2 source, PAR 1.028
build 518 - DXVA good
MPC-HC 1.1.0.0 - no DXVA, filter properties indicate DXVA, but all I would get is a black screen.
MPC 1.1.0.0 w/ PDVD8 h264 codec - DXVA good.