I have written a decoder using MS' MFT H.264 decoder contained within msmpeg2vdec.dll. On my home and dev systems, this is version 12.0.9200.16426 dated 1/3/2013.
Then on a clean Windows 7 QA system the decoder does not work as documented. The version there is Version: 6.1.7140.0 Date: 07/13/2009. I found the problem as well, the 4 year old decoder does not support I420 as the YUV output format, but NV12 works.
It seems virtual machines all have this problem, incl my Parallels Win7 on a Macbook, with all Windows Updates applied. So I am guessing the update msmpeg2vdec comes with DirectX updates with video cards, but who knows ... as there is no documentation for these revisions or how the decoder gets updated.