I believe exzap linked to this issue in decaf emu before: https://github.com/decaf-emu/decaf-emu/issues/229

If it was just play(h.264video) then it would be, but instead it is some variation of

H264DECMemoryRequirement  
H264DECCheckMemSegmentation  
H264DECInitParam  
H264DECSetParam  
H264DECOpen  
H264DECBegin  
H264DECFindDecstartpoint  

where many of the above are called more than once and have various unknown parameters. I don't know what the Wii U games do, but in other games the video can play in the background in windowed areas that are translated and skewed or have soft subs added to them. The complete list is:

H264DECBegin  
H264DECCheckDecunitLength  
H264DECCheckMemSegmentation  
H264DECCheckSkipableFrame  
H264DECClose  
H264DECEnd  
H264DECExecute  
H264DECFindDecstartpoint  
H264DECFindIdrpoint  
H264DECFlush  
H264DECGetImageSize  
H264DECInitParam  
H264DECMemoryRequirement  
H264DECOpen  
H264DECSetBitstream  
H264DECSetParam  
H264DECSetParam_FPTR_OUTPUT  
H264DECSetParam_OUTPUT_PER_FRAME  
H264DECSetParam_USER_MEMORY  

I'd imagine getting it hard coded to work for a few videos would work, but it might break on other videos in the game which might do some effect to the video, or even other games where it would of been better to just skip the video.