i havent used the broomstick method but id have been happier to see a bigger pull as i believe (i may be wrong) that its not just breaking the bones, its detaching the spinal cord that counts. a bigger pull also leaves the cavity for the blood to drain to. and its reassuring to feel an obvious break to the bone. in my experience, if you dont give the neck and cord a good pull then the neck can be broken but the bird is still alive and watching you. snap the cord and its away.
i also go by when the eyes are shut, in this case it was 1min. and that was when the death reflexes started.
death isnt instant anyway in my opinion, thats just a myth. it takes time for the brain and heart to stop working.
the bird did die quite quickly and quietly though. sometimes they flap for ages, we hang them for at least 5 mins until they have stopped, as they keep going long after they are dead.
but in answer to your question id say it died at 1 min at the latest, and that was actually not alot of movement for a dead bird as he was holding its wings. if you held it by its feet only it would have flapped alot more, and if you put it down on the ground it would have took off across the ground.