Disturbing new video shows a mugger smashing a man in the head with a brick — knocking him unconscious — before he and an accomplice pick the victim’s pockets. The clip, released Thursday, shows the 53-year-old victim pushing his bike into the lobby of a building on East 165th Street near Tinton Avenue, part of NYCHA’s Forest Houses, around 2:10 p.m. Saturday, cops said. A moment later, one of the suspects comes up behind him and strikes him in the back of the head with a brick — knocking him out, according to cops and the clip. The brazen suspect then pushes the victim to the floor, the footage shows. A second suspect then walks up to the helpless victim, delivering a swift kick to his face, the clip shows. Both men then rifle through the victim’s pockets and tug on them until they rip his pants, the video shows. They took off with the victim’s cellphone and wallet and ran out of the building into a nearby one, cops said. The victim was taken to Lincoln Medical Center in stable condition. Cops are still searching for the suspects, both of whom appeared to be in their 20s, police said.