p5 VS go-gst

you could instead look into a pure Python implementation such as p5py(https://github.com/p5py/p5) which I can highly recommend

Or look at at this: https://github.com/p5py/p5

Your other option would be to use the p5 python package(https://github.com/p5py/p5). It's a pure implementation of the core ideas of processing in python. There is a little bit of manual installation but it works really well. You can also use other installed library's and the latest python version instead of Jython.

I don't know how low level you want to go, but assuming you don't want to re-implement video codecs then GStreamer is probably a good place to start, it allows you to create modular video pipelines and it has Go bindings (although I've not personally used them).

For the latter I have gstreamer bindings here https://github.com/tinyzimmer/go-gst , but you could potentially also implement yourself with other libraries tuned to the purpose.

I noticed you have some gstreamer examples which is awesome! In case you are interested, I maintain bindings also (and the app libraries are included) if you wanted to remove some of that internal boilerplate :).

If CGO isn't off the table, gstreamer can do some interesting stuff with the app library. I have bindings here. This example plays with "dynamically" producing image frames.