@spaceinsomniac: They were told by the Department of Justice to not release that video because it was irrelevant. Additionally if they were simply complying with requests for information why has there been no autopsy of the murder victim, no statement or account from the murderer and no attempt to interview witnesses?
They did release the name of the officer, which I'm sure they also didn't want to do. I would think most of the other things you mentioned will have to wait for court, especially a statement or account from the accused. I also don't understand how they could be told by the department of justice not to release a video that state law requires them to release.
I will agree that it was incredibly poor timing for information that should have waited until trial, but it will be absolutely relevant to a defense attorney attempting to establish Brown as someone who had reason to fear being stopped by the police, and had a higher likelihood of resisting arrest or fighting with an officer.
I just hope several people saw the entire altercation, and not just after shots were fired. I think people testifying that they never saw Brown go for the officer's gun is the only thing that will absolutely ensure a guilty verdict. Everything else could possibly be blamed on panic / adrenaline, however true that may or may not have been.