Except, of course, for the part where that's not at all what happened. As it turned out, the protesters were actually chanting, "We won't stop, we can't stop, 'til killer cops, are in cell blocks." The news report left out those crucial last four syllables.
This was not an accident. The audio of the video, which was being presented by reporter Melinda Roeder and cameraman Greg McNair, was deliberately altered by looping of the phrase "killer cop" to make the protesters sound like a pack of bloodthirsty psychopaths.
They needed those extra two seconds to cover more sports.