Problem with object rotation(mouse look)

[emc2]

Hi,
I have small problem with object rotation
my object is parented to player camera, when I press key object is rotated by mouse look action and when I press key there is a jitter sometimes

take a look (from 19 second to 23):

https://www.youtube.com/watch?v=uBL7zscezQY&feature=youtu.be
s

I hope you understand what I mean

thanks!