I set up my Pi running
gst-launch-1.0 -v v4l2src device=/dev/video0 do-timestamp=true ! video/x-h264, width=640, height=480, framerate=30/1 ! h264parse ! queue ! rtph264pay config-interval=10 pt=96 ! udpsink host=192.168.0.114 port=5600
On my Ubuntu VM I run
gst-launch-1.0 udpsrc port=5600 ! application/x-rtp ! rtpjitterbuffer ! rtph264depay ! avdec_h264 ! videoconvert ! autovideosink
and I see the video from the camera.
When I run QGC and enable the VideoReceiverLog output I get the following which seem to suggest that it should be working but I get nothing.
VideoReceiverLog: Starting decoding "udp://0.0.0.0:5600"
VideoReceiverLog: Decoding started "udp://0.0.0.0:5600"