He, or she as Di thought, is a beautiful bird!
I had a look at the video - what a fabulous example of recall training ie. cue-ing her to fly to your arm and then her flying!
Did you reinforce her flying to you with a treat? If not I would, or else the behaviour will gradually die out, especially if it is followed by something aversive like trying to touch her head.
The video does show the bird uncomfortable with your approach from above, as Diana pointed out. There is a lot of lunging. What you are actually doing here is teaching her to lunge/bite more. You could try approaching from below (ie. to stroke under the beak or cheek area), but going much slower… ie. not making contact at first until the bird shows relaxed body language, then progressing a little further. But some birds just don’t like to be touched which you might have to accept.
Is she ok with your hands otherwise? I would work on getting her to accept your hands, get used to them etc. She takes treats from you nicely which is great. Does she take small toys, play with you/your hands? Maybe concentrate on pairing your hands with good experiences (treats, toys, etc) so that she begins to trust them.
Also the “shhhhhhhh” sound might be comforting to humans but to many species of parrot it is a sound to say “I’m not happy”. What sounds does your bird make when she is happy/content? Try to copy them instead of using the “shhhhhhh”. I know the "shhhhhh" sound is very unsettling to my birds.
Parrots usually bite to say "no!" or maybe if they are exploring something. In the video she gets a treat for stepping back onto her cage top which is great! Because she takes treats so nicely from you, you can use them for teaching her other things like stepping up on you without biting. Ask her to step up onto your arm and immediately reinforce with a treat. But hold the treat high so that she has to reach up to get it. She can't reach for the treat and bite you at the same time. Then immediately get her to step off your arm before she even thinks of biting. Gradually you can train duration which is the amount of time she is on your arm without biting.
The more a parrot bites the more he/she is learning to, which is why it is better to try never to evoke a bite in the first place, by heeding body language and using sensitive training.