If you really want to see magic, take a test sample of YUV420 video and AV1 encode it to an extremely low bitrate at like 720p, 24 fps to simulate something like the jerky handheld front-phone-cam in the example URL. Keep lowering the bitrate until the quality become unacceptable. Then compare it to the same bitrate/approx total file size in H264 and how bad it looks.