Trying to understand pressure regulator

[EDIT2] (at top to make sure visibility) All good, as explained in one of the posts. I shouldn't expect pressure regulator to work directly at faucet. (Use tee or splitter) Here is video https://youtu.be/gp4aquT19LA

[Just started looking into drip irrigation] I'm using rainbird 25PSI pressure regulator along with pressure guage. (https://www.amazon.com/Rain-Bird-HT07525PSI-Irrigation-Regulator/dp/B0049C5FZA)

Pressure guage measures about 70PSI without regulator (directly at garden faucet), however this doesn't really change even after using pressure regulator.

Am I misunderstanding pressure regulator? or is guauge/regulator broken?

[EDIT] Here is what I'm talking about (in both cases it reads about 60PSI):