Tinkering GStreamer (0) : See myself from PC Camera

$ gst-launch-1.0 v4l2src device=/dev/video0 ! videoconvert ! ximagesink

Looks pretty clear: source is /dev/video0

ref:
https://github.com/umlaeute/v4l2loopback/issues/174
https://stackoverflow.com/questions/23354041/gstreamer-video-stream-error-and-breaks-dev-video-source