The bit rate recorded by camera is about 500kbps, which is about 3megabytes of data traffic per minute.
If  Continous Video Recording service is on, it consumes 3megabytes of data traffic per minute.
If Event Video Recording service is on, each event consumes up to 1.5megabytes of data traffic.
If the motion detection feature is enabled with image notification, a picture consumes about 30KB.