But can the Legislature expropriate private property by means of an FOI law? If a private citizen owns the copyright, and then it comes under government control and anyone can get it by FOI, isn’t that an expropriation of the private citizen’s copyright, without compensation?
I don’t think the citizen has lost their copyright to the video. They could still sue, and probably win, if someone tried to use the video without their permission and outside of the fair use exception. So, copyright is still intact, but it’s possible that third parties can obtain copies of the video via the Texas Public Information Act (not certain about that though).
As a general matter, only materials created by the state or its subdivisions are public records. Records seized from private parties by an agency arguably become public records. However, in most states the law makes records of active criminal investigations specifically exempt from the public record. There’s an interesting discussion here, where a Pennsylvania court held that the cops didn’t have to turn over a casino’s surveillance video because it had only become a “record” of the state in the course of a criminal investigation.
Just making copies of a video without the permission of the copyright owner is normally a breach of copyright. Fair use comes into play later.