Holy moly, what a beating! But I finally got this example to work
For various reasons I had to create a new virtual machine, install a newer version of Linux and spend much time troubleshooting this simple script. I eventually found that a missing component (webmmux plugin) was in a “good plugins” package I hadn’t installed, but partially because there seem to be at least three different versions of gstreamer available and the names didn’t match the packages I had available.
It actually is the wrong codec, but I knew that when I started. The goal was to get it working as designed and then see if I can change the encoder to h264 and see how I can move the components around.