In this video, two cops are seen detaining a black man. The casual racism and hostility to a peaceful bystander is appalling in any case, but these cops have made a worse error: the man they've handcuffed identifies himself as an FBI agent. They free the man at once.
Here's a longer cut of the video.
Whether or not the man is really an FBI agent, it's a great illustration of law enforcers being predatory bullies whose behavior changes completely around perceived power and privilege.
Correction: the cops are not from NYPD and this occurred long before this weekend's protests.