Is dynamic flexibility good enough?

Hey guys I've been trying to improve my flexibility for roundhouse kicks a while now using the advice of Shane from fightTIPS but i dont seem to be improving.

I was just wondering if all im interested in flexibility for roundhouses would dynamic stretching alone be enough and any dynamic stretching plans for roundhouse kicks you guys use would be appreciated.

Many thanks

Heres the video of what im doing currently
https://youtu.be/ajLaXML8YLM