The phrase "reasonable expectation of privacy" is linked to the Fourth Amendment in the same way the phrase "I'll be back" is linked to the Terminator franchise. In essence, it dictates the applicability of the law guaranteeing "the right of the people to be secure in their persons, houses, papers, and effects." Given that the Supreme Court has always treated American homes as more or less sacrosanct, it seems likely that there's nothing to fear from the government (unless you give law enforcement probable cause). For civilians, privacy laws have traditionally done a pretty good job of protecting Americans from invasive or inappropriate photography or recordings. That does not mean, however, that recordings don't go public.