I’m going to address to Helen then 
You’re playing with the finger tips but I think your putting to much curl into your fingers causing the tension in your hand and fingers. You could try flattening out you fingers a little to relax the fingers.
I also noticed your pulling some of the strings downwards as you’re moving up and down the scale. This is something to be avoided. I thing flattening your fingers will help with this as well.
Other than that you’re doing pretty good and after finding the sweet spot with the fingers you relax and get faster.