In all charity, folks who have responded here are ill-informed. The ACLU in Pennsylvania has a free pamphlet they distribute on this topic. I highly recommend you read it. Also, see these articles.
https://www.aclupa.org/issues/polic...-observe-police/taking-photos-video-and-audio
https://www.acluga.org/en/know-your-rights/when-taking-photos-and-making-video-and-audio-recordings
YOU HAVE THE RIGHT TO VIDEO RECORD ON DUTY POLICE
If the police retaliate against you for recording them, You might have a case against them under a federal law, 42 U.S.C. § 1983 (“section 1983”), for deprivation of civil rights. Your claim might involve your First Amendment right to record and your Fourth Amendment right against unlawful arrest.
https://www.aclutx.org/en/know-your-rights/your-right-film-police
Currently, the following U.S. Courts of Appeals have recognized the First Amendment right to record the police and/or other public officials:
First Circuit (with jurisdiction over Maine, Massachusetts, New Hampshire, Puerto Rico, and Rhode Island): see Glik v. Cunniffe, 655 F.3d 78, 85 (1st Cir. 2011) ("[A] citizen's right to film government officials, including law enforcement officers, in the discharge of their duties in a public space is a basic, vital, and well-established liberty safeguarded by the First Amendment."); Iacobucci v. Boulter, 193 F.3d 14 (1st Cir. 1999) (police lacked authority to prohibit citizen from recording commissioners in town hall "because [the citizen's] activities were peaceful, not performed in derogation of any law, and done in the exercise of his First Amendment rights[.]").
Seventh Circuit (with jurisdiction over Illinois, Indiana, and Wisconsin): see ACLU v. Alvarez, 679 F.3d 583, 595 (7th Cir. 2012) ("The act of making an audio or audiovisual recording is necessarily included within the First Amendment's guarantee of speech and press rights as a corollary of the right to disseminate the resulting recording.").
Ninth Circuit (with jurisdiction over Alaska, Arizona, California, Guam, Hawaii, Idaho, Montana, Nevada, the Northern Mariana Islands, Oregon, and Washington): see Fordyce v. City of Seattle, 55 F.3d 436, 438 (9th Cir. 1995) (assuming a First Amendment right to record the police); see also Adkins v. Limtiaco, _ Fed. App'x _, No. 11-17543, 2013 WL 4046720 (9th Cir. Aug. 12, 2013) (recognizing First Amendment right to photograph police, citing Fordyce).
Eleventh Circuit (with jurisdiction over Alabama, Florida and Georgia): see Smith v. City of Cumming, 212 F.3d 1332, 1333 (11th Cir. 2000) ("The First Amendment protects the right to gather information about what public officials do on public property, and specifically, a right to record matters of public interest.").