Mr. Surveillance,
Along this same line. I have a potential customer who has a dog kennel and they would like to have an audio mic installed in their kennel which is 100' from their office. They do not care about recording only to view and monitor the kennel when opened for business.
I am in the U.S. and where it is not being recorded I can not see where this is illegal but it sounds like you are knowledgeable in this area and you can provide some insight.
At this time there is no desire for recording and we told them about the issue surrounding audio recording. But this as I mentioned is not being recorded only monitored during work hours.