She comes across to me as simply totally immersed in what she's doing - not unlike an elite athlete competing or top musician performing - I've seen the same in some martial artists as well.
I think it's gone through enjoyment and out the other side into something else altogether.
Impressive isn't she, although this might show her abilities off a little better.
https://www.youtube.com/watch?v=eKLaJDIoWfI
G