Compiling and running videoGrabberExample

Hi there,
First, thanks for such an excellent resource (i.e. OF)!
I’ve been trying to get the videoGrabberExample program up and running, but while the GUI window pops up, I only see a black screen, and in the terminal I get the warning:

[warning] ofGstVideoUtils: update(): ofGstVideoUtils not loaded

and using export GST_DEBUG=3 simply highlighted the main error:

GST_PIPELINE grammar.y:740:gst_parse_perform_link:

I am working on Elementary OS 5.1.7 Hera (built on Ubuntu 18.04.4 LTS) that is dual-booted on a Huawei Matebook X Pro, and the webcamera is called (rather unhelpfully) HD Camera.
I can get the videoPlayerExample to work, but not the grabber. Am I just doing something dumb?
Let me know if you need more details.

Did you install the video codec?

Via the ./install_codecs.sh in scripts/linux/ubuntu ? If so, yes, I did it today, along with a re-run of install_dependencies.sh . If this is not what you mean, what do I need to do?
Thanks!