Hi
while not having tried that myself yet I can offer a wild guess. Looking at video with hardware acceleration Microsoft used to rely on DXVA with has only Direct3D 9 interoperatability.
What Direct3D 11 seems to lack as of now are the required surface formats to support native YUV encoded surfaces such as NV12 or YUV444 or similar formats.
However, looking at the Direct3D 11 texture format options you can already find enumerations for these formats along with a hint that these formats are Windows 8 only. So I think that Microsoft is about to get rid of DXVA with the release of Windows 8 and will place the surface formats supporting hardware accelerated playback of video formats right inside Direct3D 11. It also looks like Direct3D 11 would become part of the Windows Platform SDK and won't be a seperate SDK any longer.
Again, all these statements are just wild guesses but if these become true than I would say that you could simply use ID3DTexture11 instances directly as input surfaces for the Intel Media SDK decoder.
Maybe someone who has tried a pre-release of Windows 8 along with the new texture formats in Direct3D 11 can give more details here.
regards,
Stefan