I got the cuda working in movie edit pro 2016 premium mainconcept mpeg-4
You need to download the driver http://www.nvidia.com/object/win7-winvista-64bit-260.99-whql-driver.html
Extract it do not install, then use 7zip to extract 3 files 2 nvcuvenc.dl_ one is a 64 bit the other is a 32 bit after you use 7zip to extract them they will have the full dll extention nvcuvenc.dll. Put the 64 bit one in the windows\system32 folder and the 32 bit in the windows\syswow64 folder.
Now you also need to use 7zip on the nvcuda.dl_ to extract it with the full .dll > nvcuda.dll, you CANT just rename the dl_ you need to extract all 3 on the file not remame.
THEN put the nvcuda.dll in the windows\system32 folder. Start your movie edit pro and you will now have cuda hardware encoding and no mpeg-4 error on the mainconcept mpeg-4 codec
mainconcept mpeg-4 will only work with the 260.99 cuda versions, it does not matter that the 260.00 is not for your video card as you are not installing it, just the 3 file for cuda that are in them. My card is a gtx 650 ti but it will work with any geforce that has cude.