I always feel like somebody's watching me

That could be the case if you are touring a home with security cameras!

In Texas, there's no law that says agents have to inform their buyers that there are cameras; but in many cases how would they know? It is not usually specified in the MLS listing. It's a good idea to mention before showing homes that there may be surveillance cameras recording video, audio, or both. 

From the sellers' standpoint, it would be helpful to hear what buyers say about your home as they are viewing it. However, it's illegal in Texas to record audio without someone's knowledge unless you are speaking with them.

You can record silent video as long as it's not in a private area, such as the bathroom. Recording video and audio together during a showing is problematic.

If buyers find out they have been illegally recorded, they can bring a civil suit for up to $10,000 per occurrence as well as other costs. Talk about your buyers' impressions when you're finished with the showing. The sellers can get their showing feedback from you, the agent.