@longjon,
You are speaking from within an ideological bubble, and you are conflating the issues.
1. I do not support protesting a fair trial. A trial is decided by 12 people who have patiently listened to all of the evidence presented and who aren't allowed to consider the protests... and besides by the time the protest happens the
2. The failure of the Black Lives Matter movement to control, or even consistently condemn violence has severely damaged their message.
3. I feel like the left is tacitly condoning violence in this trial. They seem to be preparing another round of excuses. There was a recent piece on NPR where someone was seriously arguing that throwing a molotov cocktail into a police car shouldn't be punished because it was a "protest", and no one contradicted her. This messaging from the left is irresponsible.
4. I don't see how anyone (but the most ideologically extreme) can condone or excuse the behavior of the police officer in this George Floyd case. It was unprofessional, savage and showed complete disregard for the life of the person in his care. Other police officers (including my son) are disavowing what he did.
5. In my opinion The complaints behind the Black Lives Matter movement are unquestionably valid. There is reason for anger. I raised two men of color and dealt with the racism they faced.
The angry protests you see are reflecting a real problem in our society.