It was the agitators themselves who discovered the flyer when they walked inside the 30th Precinct for a community board meeting.
This is how Christina Gonzalez Nysid, who captured the flyer on video, described it on Youtube:
Walked into the monthly 30th Precinct community board meeting to discover our own faces hanging on the podium. It reads
Be aware that the subjects are known professional agitators that live at [our address posted on poster]. Above subjects mo is that they video tape officers performing routine stops and post on youtube. Subjects purpose is to portray officers in a negative way and too deter officers from conducting there responsibilities. Above subjects also deter officers from being safe and tactical by causing unnecessary distractions. Do not feed into subjects propaganda.