I would recommend that you look again at gst-python! It is not coupled with pyGTK. You can use it completely separately, with no dependencies on either the Python bindings or the C libraries of GTK. I’ve written several command-line utilities that use gst-python and not GTK.
It’s true that the gst-python docs are not so great. However, the documentation for the C API and modules is really very extensive, and the mapping from the C API to the Python API is very straightforward. And there is a very active Gstreamer community and I had good luck finding help on the mailing lists and IRC!