You must post a sign announcing video surveillance on private property.
Fiction. You do not need to post signage stating that a property has video surveillance devices capable of recording. Video recording is generally allowed anywhere on private property except where there is a reasonable expectation of privacy, like a bathroom.
Audio recording is different. The Federal Electronic Communications Privacy Act and the Texas Penal Code prohibit audio recordings without the consent of at least one person involved in the conversation.
If there is a conversation, and there are two people, and you consent to recording the conversation, it’s possible to record without the other person knowing because you’ve consented to yourself to record. Something doesn’t make sense.
I believe that the law varies by State. Some states require both parties to consent while other states require only one party to consent. Texas is a one party state. There are some exceptions. Suggest verifying with an attorney.
What about Ring cameras that capture audio as well as vidoe?
My Ring doorbell has a voice that says “Hi! You are currently being recorded.” I wish Ring would make it easier to find that setting. I came upon it by accident and have no idea how I did it.
So listening live is OK if the conversation is not being recorded even if none of the people you spy on know you’re listening…