Australia went through a few accidents some 20-30 years ago which brought the subject of cameraman’s harnesses into the spotlight, and we now have excellent ones available from a few companies. The best uses a ‘3 ring circus’ of overlapping metal rings to hold the harness strap onto the harness, the rings being locked in place by a plastic rod which goes through a sheath to a ripcord pull velcro’d to the top left harness.
Easy to release under any strain, the setup is based on parachute harness principles and is commercially available plus covered under CASA requirements. Not to be secured to the aircraft when the cameraman is strapped into the normal seat harness. The cost is both reasonable and affordable for any company serious about safety.
A backup webbing knife is usually added to the harness as a secondary release, but not (IIRC) mandates.