Route wire from bumper mounted backup camera into interior

I'm installing a flush mount backup camera in my 2001 TJ Wrangler.

I've been watching videos (for example: https://www.youtube.com/watch?v=NdL3aKfhqqQ ) and I think I have all of the steps down save one: routing the cable from the bumper to inside the front dash. This is the part they never quite seem to show. It's sort of "magic".

And that's the ONLY part I'm unclear on.

Can anyone suggest: where is the gasket or portal that allows me to get from the rear bumper to "inside" the vehicle?