The NVIDIA NVCUVENC was widely used with video conversion programs. Mostly the CUDA engine was being used with H.264 video encoding.
The NVCUVENC is provided by a DLL that was removed subsequent by NVIDIA with more recent drivers.
NVCUVENC was deprecated with R337 branch in favor of the NVENC which offers superior video quality. NVENC is supported on Kepler based GPUs and higher. NVCUVENC works on Maxwell and Pascall cards fine.
If you have a program that uses CUDA, then you may want to use 337.88 which is the last WHQL version of R338 that still has the DLL available.
We feel that it’s arrogant to break backwards compatibility. The DLL was not malicious and only stood to enable CUDA compute for any application. NVIDIA markets CUDA which is why we are very disappointed with the change.
It may take some time before new video conversion programs are developed to cope with the change. The problem is that there are not any free alternatives available immediately.