That video was released in a news conference on Monday morning. Police also announce at the news conference that the reward for information has been raised to $69,500.
The video shows the moments leading up to Officer Walker's death as he walked down Cecil B. Moore Avenue around 6:00 a.m. Saturday.
The video shows the suspects trailing him from the opposite side of the street.
Police say the suspects likely didn't know Walker was a police officer when they approached him, pulled out a gun and demanded money.
Police say Ofc. Walker pulled out his off-duty weapon at which time he was shot in the chest, stomach and hand.
The shooting happened just a few blocks from his 22nd District station after finishing his shift, police said. He wasn't wearing a uniform.
The 19-year-veteran, who was unmarried and had no children, was pronounced dead at a hospital in a city where on average nearly one person has been slain every day this year.
If you have any information about the suspect or the crime you can submit a tip by dialing 215-686-TIPS (8677), text TIP to PPD TIP (773847) or through phillypolice.com.
Officer Walker remembered at vigil
The family of Moses Walker, Jr. gathered at the North Philadelphia murder scene to remember a man who was dedicated to his family, his faith and his brother and sisters in blue.
"My son served," said the officer's mother Wayne Walker. "He served everybody. He served the city. He served his family. He served his nieces and nephews. I want to thank God for my son."
"Whatever it was about, it wasn't worth taking his life. You took him away from his family. You took him away from the people who loved him and the people he loved," said Anthony Walker.
Walker is survived by his mother and 6 siblings; a tight knit family struggling over his senseless murder.
"I love my brother, and I know my brother is up there looking down on all of us, and I know he hurt, because we are hurt," said Walker.
Funeral arrangements have not been announced.