Worth doing!
Briefing is something I've always done with new passengers whether fellow pilots or SLF. It was always advised as a precaution and to assist any potential insurance claim helping to avoid insurance companies asking "did you explain what to do to the passengers before taking off?". (Or in worst personal case, if they had to ask the passengers if the pilot - me, unable to answer due incapacity of whatever sort - had briefed them).
I simply say "for insurance purposes, let me explain what we do if it goes quiet" and then run through doors, windows, order of exit (back seats first) etc. And explain how unlikely they will need to know, but best they do.
It takes 3 minutes and apart from the claim aspect, could really help.