I have done it in front of her a few times. I think she would rather help than watch, which is fine with me.
She will do it in front of me often. Sometimes she just offers to "do herself" for me, or I can ask her. She will even use toys in front of me often as well.
Sometimes she will just "jump in" to finish herself if I am teasing her just a little too much. (Hench, my handle.
)
In fact just the other day she jumped in rather unexpectedly. When I asked her why, she said it was too far off. (I have this "trick" I do with a clean, soft, long bristled make up brush. I guess it just wasn't cuttin' it!)