That is called good technique. Of course relaxed is good. For example, keeping a relaxed arm in a serve.
But beware of anyone peddling feel, effortlessness, holistic approach, etc.
They will twist the words to accomodate any situation. You can never prove them wrong. Saying Murray is relaxed is easy. To understand what it means and it it useful to you is a different matter. I play my best when I am relaxed on Sunday compared to on Friday night. But it is not to be made into a philosophy and packaged as some secret.
The guy's forehand analysis is very good - rotation and extension through the ball towards the target.