That's the real art of an entertainer.
Not the knowledge of your craft, not how many hours you practice, not how witty you are at the party, not your natural born talent...
But how you perform in front of a camera when the director says "Action!"
Camera Charisma is a separate skill from general charisma.
A person may be very charismatic one-to-one, or in a familiar situation, but if they don't have the confidence & specific skill set to capture an audience's attention, then they do not have camera charisma. This is something I'm realizing, and working toward myself.
Likewise, a person may be a bumbling loner in real life... but when the camera turns on, watch out - you might witness a once-in-a-lifetime performance...