The official UVC app can receive push notifications from the NVR when motion is detected. It would be great if HASS could fetch these as well.
If it´s not possible to get it using the API maybe something can be done with the motion.log file?
This file register start/stop of every motion:
type:start event:6979 clock:1508717358 (CAMERANAME) in app-event-bus-6
1496860573.273 2017-06-07 20:36:13.273/CEST: INFO Camera[0418D623836D]
type:stop event:6979 clock:1508724121 (CAMERANAME) in app-event-bus-3