A wonderful aspect of that video is that Cranston goes beyond the advice, he explains what it means to him and that he had to adapt it to his situation. He doesn’t simply say “Do this,” he shares a path to his advice.
One can understand his advice using the lens of the dichotomy of control.
When an actor goes to an audition he goes there because he wants a job. That is what the audition is there for: finding the actors most suited for a film one wants to create. It’s an objective that is owned by the auditors. They have an idea of how the actor should contribute to the film as well as a list of criteria an actor may not be able to answer, for example, based on his physique. And there is no harm to this, it’s because he is who he is. There are things about us that cannot be changed or that we don’t want to change for others.
The actor who participates in the audition can want the job and may even need it. But he isn’t in the position to decide if he gets it. That is outside of his control. However, what an actor can do, is perform as an actor and as well as he can. That is how the actor chooses what is within his control.
A challenge of accepting this view on his job is to accept that his idea of the character has to be his own and cannot be one he will be told to deliver.
It’s not the whole job though. There is more to it. And that is probably what Cranston means with “once I adopted this philosophy.” He had to discover for himself what it means to be an actor doing his best in an audition.
No one can tell you what it means for you to do your best.
For him, as an actor, it is: “An actor is supposed to create a compelling, interesting character, that serves the text. You present it in the environment where your audition happens. And then you walk away.”
Knowing what your job is is a good start.