Most smart fitness mirrors have a front-facing camera that is activated only during workout sessions. Some even come with privacy covers or an on/off switch. The cameras and sensors are built into the mirror to offer real-time posture correction recommendations and help instructors give personalized feedback.
However, not *every* smart mirror has a camera. If you're not a fan of inviting a video camera into your personal space, that could be a good thing. But if you want the kind of custom feedback and form correction that you'd get from an in-person training session, the camera is a huge part of making that happen.