indeed a direct implementation via the Ncuvid API inside ffdshow would rock so selecting Nvidia in the Dropdown instead of libavcodec and then adding Nvidias De-Interlacer to the De-Interlacing Options
Leeperry there are already a lot of DXVA Decoder available MPC- Video Decoder, Cyberlink , Intervideo (Corel), Arcsoft, Elecard (DivX) currently