You can measure it e.g. on speedtest.net. See the upload speed value and ping time. Be sure you are on the same network as the camera. In addition use the Diagnostic Tool which is part of the Camstreamer App for more accurate evaluations.
If there exist an already outgoing stream, then the result which is being displayed is additional bandwidth.
If no outgoing stream exists at present then the result that is being displayed is total available bandwidth.