For all DVR model DVR8516
Log in client software. (CMS software)
(admin ID: SYSTEM, password: 123456)
(If you didn't connect your DVR yet, click 'system config' -> 'device manager' -> 'add device' (it's a green button at the top), after you connect your DVR, click 'Live' to check if your video work properly.)
Cilck 'system config' -> 'user manager'
(at right side banner)
Click buton 'add user', and setup a user name (this is the ID when user log in)
In the 'Live' section, limit the cameras.
Test your limited video using the user ID you just setup.