In the video, there are a few times when her lips don’t look as if they’re in synch with the singing.
The audio is out of synch through the whole video, not just her singing. It’s a low-quality streaming video, what do you expect?
Watching her sing for the first time, it’s easy to be skeptical that it’s really her voice. It sounds so much like an adult’s.
Charlotte Church at a young age also had an impressive singing voice, but the sound of her voice matched her age.