Stuff like this makes me thankful I only have boys. The sexualisation of girls at such an early age is just scary. Yes I'm sure it's all a bit of fun, but if a 6 year old is pouting and fluttering her eye lashes like this already, it's scary to think how early all the other adult things will come around.
I personally wouldn't be encouraging it. Then again, I have no idea what else her parents encourage. this could be one of a thousand other hobbies of hers, but this definitely isn't something I would allow.