But no one has conclusively shown that Jamar Clark wasn't cuffed. There is insufficient evidence either way because either the cops or the witnesses could be wrong and the DNA evidence is only conclusive if you really, really want it to be. And while Michael Brown might have contributed to his own demise, the situation in Ferguson was much larger than him. If you followed what was going on in Ferguson, you'd know that the police departments there were getting substantial funding via an oppressive regime of tickets and fines. While Brown might have been a rhetorical focus for the initial protests, they were actually about a huge problem separate from Brown (a problem which is changing, thanks in part to the protests).

You want suspects to be treated innocent until proven guilty? Do the same with the police.

I'm not a criminal court. I don't have to use their standards of proof. Which is great, because the world would cease to function if all facts needed to be determined via trial.

And for police shootings, there's no guarantee that the results of an investigation will be consistent with reality. These are investigations conducted by people who are biased towards the police officer. Generally the results of these investigations are just inconclusive enough to blanket the cop in reasonable doubt.

The fact that you personally don't think the protests are justified doesn't mean they aren't actually justified (or useful).