The pyopengl-video library is a small hack that lets you pass FrameBufferObjects (FBOs) directly to the local platform video encoding library (or allows you to use your existing video buffer as an FBO, depending on the platform). The purpose of the library is to allow an off-screen renderer to generate h264 in mp4 video previews of that off-screen rendering. I find that useful to allow an agent to capture e.g. gameplay demos or the like so that you can see what it is working on while you are not at your desk.

On Linux with nVidia uses NVENC. For linux with Intel or AMD uses vaapi. Windows uses D3D11 and COM. Requires PyOpenGL 4.0.0a5 or above. So far no OS-X solution.