Processing separate video streams works well with separate processes. There is some cost related to starting the other processes and sometimes libraries may stumble (e.g. several instances of ML libraries allocating all the GPU memory) but once it's running it's literally two separate processes that can do their work independently.

Multiprocessing could be a pain if you need to pass frames of a single video stream. Traditionally you'd need to pickle/unpickle them to pass them between processes.