Attorneys and witnesses have used the words "reasonable" or "unreasonable" often at the trial.
Dr. David Fowler, a former Maryland chief medical examiner who is now with a consulting firm, also testified that he would classify the manner of death "undetermined."
The death of George Floyd in Minneapolis led to worldwide protests over police brutality and racial injustice.
Picking the 12 members of the jury is expected to take three weeks as prosecutors and defence attorneys grill potential jurors try to ensure impartiality.
The video shows officers forcefully restricted Jozef Chovanec's movements in a cell at Charleroi airport, with one officer sitting on him for a long time. Another officer made an apparent Nazi salute during the incident.
Cedric Chouviat, 42, died after being pinned to the ground by arresting officers. Video footage of the arrest reveal he said "I'm suffocating" at least seven times.