Yes that is actually a police officer in that video, confirming what Occupy activists have been saying for months is standard operating procedure in dealing with their protests:
Tales of reporters, protestors and citizen journalists being threatened or arrested for filming law enforcement officials during disputes are on the rise, critics say, with Occupy Wall Street protests a lightning rod for these incidents. The National Press Photographers Association claims it has documented 70 such arrests since September and, in May, called on U.S. Attorney General Eric Holder to focus attention on the issue.“The First Amendment has come under assault on the streets of America,” the photography association said in a letter to Holder that was also signed by several other interest groups. “Police have arrested dozens of journalists and activists simply for attempting to document political protests in public spaces.”
Such allegations are ironic, given the sharp rise in police surveillance technology, which gives cops vast capabilities to film citizens, said Catherine Crump, an American Civil Liberties Union attorney.