This really is not even a close question: there is a First Amendment right to photograph and videotape police conduct on public property. See here. Once again a federal court affirmed this right:
Last week, in Martin v. Gross, Chief Judge Patti B. Saris of the U.S. District Court for the District of Massachusetts granted summary judgment in favor of our clients, finding the Massachusetts Wiretap Statute (Mass. Gen. L. ch. 272, § 99) unconstitutional when applied to secret recordings of government officials performing their duties in public. The decision is significant for its clarification of protections under the First Amendment.