According to a local police official, investigators were not aware of this video.
Kasur had last attained local and worldwide notoriety in 2015 when a gang of paedophiles running a child sex ring was busted in the city.
The gang allegedly abducted and sexually assaulted at least 280 children in the area, blackmailed the families of the victims since 2009, and even sold video clips and images of the assault.
Protesters, angry over what they believe is police inaction in the girl's rape and murder, stormed the streets demonstrating outside government buildings over what Pakistani media said was the 12th such crime in Kasur in the last one year. The situation at Kasur police station got quite tense after which police had to disperse the crowd, in which two civilians were killed.
Two people died due to gunshot wounds in clashes with police and other security personnel. It is not clear yet whether the policeman was responsible for the deaths or injuries.
Zainab had left her house in the Road Kot area for her maternal aunt's for religious lessons on January 4.
Zainab Ansari's body was found last week in a garbage bin. Police, however, clarified that the man is only a "person of interest" as of now.
The hearing in the case has been adjourned till Jan 15.
Kiran Naz, a news anchor on Pakistan's Samaa TV, hosted Thursday's bulletin with her young daughter on her lap as an act of protest.Opening her segment, she said: "Today I am not Kiran Naz, rather I am a mother today and that is why I am sitting with my daughter."Referring to Zainab, she said "the smallest coffins are the heaviest, and the entire society is burdened by the weight of her coffin". "Police are not cooperating with us", Ghulam Rasool, a family member, said. "How was our child kidnapped from a busy market?" he asked.
At least four agencies - the Counter Terrorism Department, the Intelligence Bureau, the Special Branch and the Punjab Forensic Science Agency - have been seized with the case and each agency has arrested suspects separately, while investigating the matter.
A TELEVISION presenter in Pakistan was so distraught over the rape and murder of a little girl she brought her own child on to her popular show as she spoke of the shocking crime.
Regional Police Officer (RPO) Kasur Zulfikar Muhammad confirmed that the girl was strangled to death.
She urged Punjab chief Minister Shehbaz Sharif to show the same speed in Zainab's murder case that he maintained while constructing Orange Train.