Surely you agree that an officer does have the authority to physically restrain, using appropriate force, a non-complying citizen.
Depends on the circumstance, in this case
1) The child had done nothing that required physical force, let alone assault, body slamming and handcuffs, yea maybe for an armed robber? For this - madness
2) Depends what the non-compliance is for, if the officer is being unreasonable or telling someone to do something they have no obligation to do, then no, I don't think the office should be laying a finger on them and should get on with their job - it then becomes harassment
Sorry, I didn't see your 2nd question, I wasn't evading:
Should US citizens show respect for US authorities and comply with orders?
Again it depends what the order is, if it's reasonable and in public interest, sure, if it's an officer on a power trip - no. I say again, police are public servants, not god figures that can tell people to do whatever they feel like and expect them to do it, *just because* they are police. Police are there to serve, protect and uphold the law, not be beyond it.
Respect should be shown if it is earned, wearing a police badge does not give anyone the right to respect, their actions show if they deserve it or not. Office Rambo deserves zero respect, the man is nothing more than a thug, who happens to be wearing a uniform.