According to the specification the cameras support the ONVIF standard so use the tab for ONVIF Source when adding them. If that do not work do the following:
Use the tab for Custom URL:
Set stream type to rtsp_tcp
Address:
rtsp://username:password@cameraIP:554/cam/realmonitor?channel=1&subtype=0
or
rtsp://username:password@cameraIP:554/cam/realmonitor?channel=1&subtype=1
-Henrik