Yeh I just posted that same theory on another thread. It sounded like an AK to me and it was making a clacking sound like maybe a cheap Chinese AK. But you are right if he messed up the sear pin when he took off the safety it would fire til the mag was empty. He sure didn’t fire 800 round in 10 minutes from one AK. The barrel would have melted down. Must have been using two weapons and moving from one window to another.
You can hear the AK clack from a cellphone video taken from 2000 feet away? Were you perhaps a sonar chief? If not, you missed your calling.