[gRoberts84]

For the most part, yes.

You can easily verify by simply logging all data in/out of your network that the monitor is connected to and seeing if there is any unexpected traffic etc.

Some manufacturers are known to have added backdoors or methods to access data on remote devices but the internet community love tearing things apart, dumping firmware etc to see how things work and someone ends finding it in the end.

Not that it's the correct way of thinking, but if you have anything actually worth capturing in that respect and you believe you're being watched, you'd need to findn alternative ways to access it.