How do I turn video recorder on my DVR?

First you need to go to device configuration menu and go to the Registrar/Video Recorder tab

Here you can configure the recorder mode, namely:

Select camera which you want to turn on to the recorder (up to 4 cameras)
Set interval of recording video in seconds (from 60 to 3600s)
Select Source RTSP stream with which the video will be transmitted (1 stream - highest quality, 2 streams - lowest quality)