One of the filmmakers, Jason Pollock, told The New York Times he believes the footage shows Brown trading a small amount of marijuana for a bag of cigarillos around 1 a.m. on August 9, 2014.
Brown was shot and killed after he was stopped by police officer Darren Wilson and attacked Wilson.
Mr. Pollock believes that the Ferguson police force has attempted to smear the late teenager's reputation by claiming he had robbed a store and releasing footage supporting that to show that to the media.
The video, filmmaker Jason Pollock argues, suggests that Brown didn't rob the store but was instead involved in a drug deal with the clerks. Police have said that the robbery call was part of the justification for Ferguson police officer Darren Wilson stopping teen Brown, who he said matched the description of the thief; Wilson shot Brown seven times. The video then shows the man about to leave the store, before turning around and handing the bag back to employees.
In the footage, Brown enters the market around 1 a.m. on the day of his death and approaches the counter, handing over what appears to be a small bag. "They didn't take the marijuana...maybe Michael Brown thought they would trade him cigarillos, but they didn't".
Wilson would find Brown and a friend walking in the middle of a nearby street minutes later.
He said he will release the full video today that shows the clerks rejecting a bag of marijuana. Brown was fatally shot during a confrontation with a Ferguson police officer just after that second visit to the store. The police department was aware of the footage, but they did not believe it was significant to the case, he said.
"The next day, Brown goes back to the store, with his hands politely behind his back, to get his stuff", Pollock explains.
"It's just nonsense. It's patently false, it didn't happen that way", Kanzler said of the video Sunday on MSNBC.
On Sunday night attorney Jay Kanzler, who represents the store owners, was flanked by police officers as he faced off with irate protesters demanding to know why authorities never disclosed the video. After taking a few steps toward the exit, Brown walks back to the counter and gives the bag back to the same clerk. He says the filmaker that made the "Stranger Fruits" documentery edited the footage to make it appear that a drug transaction occoured.
"It was determined that [the video] was neither relevant nor material to anything that occurred. on Canfield Drive", the prosecutor said in the news conference.
An attorney for the owner of Ferguson Market and Liquor did not immediately return a request for comment.
St. Louis County Police Chief Jon Belmar told the St. Louis Post-Dispatch he wasn't surprised that Brown was in the Ferguson Market earlier in the day. Brown's parents have filed a federal lawsuit against Wilson and the city of Ferguson; the civil trial is slated to begin next year.