Hmmm,
What is the early morning pH reading and how does it compare to the pH of this tank later in the day? May we see a pic of the entire tank? Is there a Refugium? Is there a powerhead down low shooting water up so that it breaks the surface to create good gas exchange both day and night?
Something I notice from the clips is that the tank is quite clean looking. The LR is white. Though that may be nice for you, for the Blenny that's not so good. The Starry Blenny is an herbivore. It does best in an environment that some would consider "dirty". What looks "dirty" is actually good biological growth; algae, bacteria, sponge, etc.
Consider is a compromise.
If algae is left to grow on at least one side of glass, you will notice kiss marks where the Blenny scrapes the algae with it's lips. It loves to eat soft algae growing on surfaces of rock and glass. Is PO4 removal media being used in this tank? Consider removing it at regular intervals or use less so that some soft algae growth can feed your awesome Starry Blenny.
Aloha