Hi thank you for your reply! He does this only sometimes; but often to be worried. He does know how to make other sounds like a normal scream or when he's calling for another bird.I listened to it a few times but couldn't figure out what it could be
Does he do that constantly or only that one time you were videoing it? If it's constantly he could maybe have a respiratory problem, if not he could just be trying out new sounds.
From the way his crest is he looks like my Smokey when he's singing or trying out new sounds.