What that aunty does...
Well it's like she is encouraging her because she is dancing so well...
Well there is a superstition kind of thing that if something is too well and so many people praise it something bad happens to it. Suppose a baby is very pretty so u might here people say "He or she is so cute, Nazar naa lage" may bad eyes stay away from him.
So while saying so they may do this gesture...if u notice that it is done as if swaying something aside...these are bad jealous eyes...
It is also called Nazar Utarna Sometimes people may put a black dot on the baby with maskara (specially elderly women) or anything dear to them like a new car bike etc.
Though a superstion in olden days...these days saying Tumhei Nazar na lage is more like an expression which means may God Protect you.
In the above scene she does so because she is really impressed by the dancing of the girl.
Hope it helps..But still anything not clear feel free to ask![]()