There are a number of possible crimes that you might be charged with. It would matter if this were strictly video surveillance. In the US, there are versions of 18 USC 2511 in all states, plus the federal law itself, which prohibit intercepting oral communication. Such recording is allowed if one party consents, and in a dozen states all parties have to consent. As the guy who plants the device, you aren't a party to the communication. However, it's also not clear that there is a "communication" in this context (in the event that some words are recorded). The definitions section 18 USC 2510 waves its hand, saying that
"oral communication" means any oral communication uttered by a person
exhibiting an expectation that such communication is not subject to
interception under circumstances justifying such expectation, but such
term does not include any electronic communication
and the question is, if a person speaks but does not speak to someone, is that a communication? In the course of making an audio-visual record, you might violate state anti-wiretapping law. Since 18 USC 2511 is about oral communication (or, looking at the Washington state analog, "conversation"), if the sound is off, one avoids that threat of prosecution.
There are relatively few restrictions on hidden video recording: none at the federal level. Florida has a law against video-recording a person "dressing, undressing, or privately exposing the body". Assuming the camera is not in a Florida bathroom, that's another source of prosecution avoided. There are laws against trespassing everywhere. However, if you get invited in, that's not trespassing. So there is a way to make a video recording in the US, without committing a crime.
The exclusionary rule would not make the video inadmissible, even if it were an illegal recording. Burdeau v. McDowell, 256 U.S. 465 held that
The United States may retain for use as evidence in the criminal
prosecution of their owner incriminating documents which are turned
over to it by private individuals who procured them, without the
participation or knowledge of any government official, through a
wrongful search of the owner's private desk and papers in an office.
The provision of the Fourth Amendment forbidding unreasonable searches
and seizures refers to governmental action
For the evidence to be admissible, the government cannot enter the premise (to retrieve the recording) without a warrant, but you can deliver the recording to them. There could be authenticity issues involved in this video that's just out there without proper supervision.