If there are deadlines involved, I would not let this stay as a verbal argument between you and the attorney.
Ask him in writing exactly why he is refusing to file the opposition and what he wants you to sign before he will do it. Keep copies of every email, filing, court order and message...
I would send the insurance company the police report and the full video in writing and ask them to confirm their coverage decision in writing as well.
Their insured refusing to return calls does not make the accident disappear, especially when you have independent evidence showing what...