Most modern video codecs (vp9, av1, h264, h265, etc) handle motion-less or motion compression very well with diff between frames. The newer ones handle motion

Most modern video codecs (vp9, av1, h264, h265, etc) handle motion-less or motion compression very well with diff between frames. The newer ones handle motion based frames better by shifting the next frame around to find the smallest diff. Ffmpeg just uses whatever codec configured.