Non-rev is flying on your company, or parent company aircraft with a seat in the cabin. You 'check-in' with the captain as a courtesy and so they know you are an able crewmember in the event of an emergency.
Completely disagree! Able crew member? What if I'm going on vacation and I want to have a few drinks while non revving? Are the checkin police going to tell me I can't do that either? It's ridiculous for those that think as a non rev pax using my own flight benefits that I've got to get the CA's blessing. Jumpseat is as everyone says but non revving is my perogative.