I have a hard time believing that the prosecutor can get past the “expectation of privacy” requirement in the prosecution. This was an open-to-the-public office of ACORN, with people coming in and out. Anyone could walk in at any time and overhear the conversation. I’d bet that any defense lawyer worth her/his salt would gladly take this on.
Just off the top of my head, and not being exactly sure of which of ACORN’s many divisions/entities the Baltimore office is part of, and this office’s precise receipt of direct government funds, the filmmakers claiming that they were preparing the films as part of a “Qui Tam” claim they wanted to pursue with the Feds against ACORN may be able to provide some cover.