Transcript for Ferguson protest sparked by new documentary
To be as prepared as possible. That unrest in Ferguson, Missouri, it's over a newly uncovered surveillance video that shows Michael Brown hours before he was fatally shot by a police officer. Some say it raised questions about whether he really robbed the convenience store on a later visit and ABC's Steve osunsami has the story. Good morning, Steve. Reporter: Good morning to you, George. The big question, of course, is why is this video just coming out now. And there's really no good answer for that. This new video may cast a different light this morning on the events that led to the police shooting death that started a movement. And overnight it had people protesting again with reports of shots fired. When Michael Brown was killed on the streets of Ferguson, Missouri, in 2014, this was the video police shared just days after the shooting. The shooting victim is seen with his hands around a shopkeeper's neck as he makes off with a carton of cigarillos. It's going to be a black male in a white t-shirt. Reporter: Police called what happened a strong-armed robbery and argued brown brought the same level of violence to his confrontation minutes later with the Ferguson police officer who killed him. How can he shoot with his hands in the air? Reporter: This new video from the same store suggests that brown had left the cigarillos at the corner store the night before and that people working there had exchanged the tobacco for drugs. Something that appears to be happening here. The filmmaker who discovered the video says it was recorded at 1:13 A.M. August 9th, nearly 11 hours before brown returned to the store. We're doing this for Mike. We're not just doing it to uncover for Ferguson. Reporter: Part of a documentary called "Stranger fruit" that day debuted this weekend. It was an argument over getting back his things. They wanted us to think 3450ikle robbed the store because they needed us to think Michael was aggressive with Darren, the clerk, takes the cigarillos and hands the plastic bag over the counter to Michael Brown. That's not stealing the store. Reporter: Brown's uncle said police lied about his nephew. The picture they painted of my nephew was not right. That video dispels one of the lies they was telling. Reporter: The store owner strongly deny this telling ABC news to turn around and somehow blame folks that have nothing to do with this is shameful adding it just didn't happen. This morning, St. Louis county police tell us they can't confirm the authenticity of the video at this time. Legally this changes nothing. Police say officer Darren Wilson knew about the alleged robbery at the store but had no way of knowing brown was a suspect. Whether or not there was a misunderstanding at the store has little to do with the later argument and shooting. There is no video of the argument between brown and officer Wilson and no video of the shooting. This just makes the story messier. A civil trial is expected to start next year. George. Okay, Steve osunsami, thanks. Let's talk more about it with Dan Abrams. Also, former Dallas police chief David brown an ABC news contributor. Chief brown, let me begin with you and put the question right at the top why did it take so long to get out. Should the video have been released sooner? Yes, George, it should have been released sooner. This is not the way you communicate with your citizens in your community. It just lends itself to whether or not the department is holding back other types of evidence that may be have ago different narrative. That's the question raised, Dan Abrams, but, remember, the officer who killed Michael Brown cleared by a county grand jury. Would this video have changed that. No, this is a compelling theory but let's remember, it wasn't just that a grand jury decided no the to indict. It's that the department of justice did a thorough investigation and we leased an 86-page report based on the blood evidence and DNA evidence and the eyewitnesses, based on the injury, all of that together they concluded supported Darren Wilson's account of what happened. It's also important to remember that many of the same supporters of Michael Brown initially said, well, what's the relevance of the first video? Meaning showing Michael Brown pushing the clerk and you know what they were right and I think that they would be right here which is -- The officer didn't even know he was a suspect. So what happened there while interesting and important in terms of sort of the big picture of what happened that evening isn't really relevant to what happened between Darren Wilson and Michael Brown. Do you agree with that, chief brown? Yes, but I think that one thing that we're missing, transparency has everything to do with trust. People trusting that you do a thorough investigation lends itself to revealing everything you know about Michael Brown, about Darren Wilson so that the public can make their own assessment with all of the information rather than holding back some and not having explanation of why you didn't release it. A fair point. Does this impact the civil trial. Potentially could impact the civil trial because the question would be why did you release it and what chief brown is saying, it's trust. If the jurors in the civil case don't trust the police, that's not helpful to their case but, again, it won't go to the fundamental question, the police's answer to this is they didn't think it was relevant to the investigation but I think chief brown's absolutely right that when you're talking about trust, try and release as much as possible so no questions later. Dan Abrams, chief brown, thanks very much.
This transcript has been automatically generated and may not be 100% accurate.