I ran a payrolll system
that was far from perfect. Remote access was allowed to the provider to sort out various issues that arose. This was a DOS based thing that ran on a Novell server. Buggy software and poor transaction logs/no software checking as to why it was not closed gracefully etc. Meant locked files and EOF markers not being written after Windows crashed. I eventually worked out how to fix all this myself.
However the the point being... I changed the password every time they connected, fixed and logged out. They were never very happy about having to ask me for the password each time they logged in.
A CCTV system may or may not be as high risk as a payroll system (depends where the cameras face). Still, why can't engineers ask for the password so they can login to fix? No one should have admin access to any system except the administrator.
I am old school, I will die old school.