Thank you so much for your blog and You Tube link. My 5 year old daughter does almost exactly what your girl does in the video. We actually found her movements quite endearing and she has done them since she was 3 months old. She does it maybe a dozen times a day when she is excited, or very pleased with herself, or very intrigued by something.
It was only because she is starting Kindergarten that I was concerned other children might make unkind remarks to her and so I started Googling "involuntary hand movements". To my utter surprise I found the term "motor stereotypies" and that some children are medically treated for this.
My daughter did wonderfully in preschool and is very bright and social too and in dance, swimming etc. no problems developmentally.
I will discuss it with my GP and Naturopathic doctor just to be reassured.
Her teacher also shared a website with me for a centre whose treatment philosophy is to not use drugs and there are practitioners throughout the states. The Handle Institute: www.handle.org
Thank you again, It is wonderful to not be alone. C