[HereInTheHeartland]

Probably passenger or flight attendants.
Sounds like the pilot went back to do something. Co-pilot stayed upfront.Was the pilot trying to troubleshoot a problem? Cockpit door was then left open so access was there from the passenger area.
Maybe as plane came down in altitude some passengers regained consciousness and tried to help.
It sounds like the plane circled an area while on autopilot for awhile.

[Rokurota]

Maybe as plane came down in altitude some passengers regained consciousness and tried to help.

My understanding was that the fighter pilots observed this at 35000 feet. Fishy.