When I was first rehabbing my back I would do bridges (not neck bridges). This discussion brought them back to mind.
I've started doing these (while lying on the floor in the evening watching TV...I learned our couch is bad juju for my low back). It's like the glute bridge, but after I raise my hips up, I also raise my shoulders off the ground. The neck is then engaged but not extended. I also press down with my hands. I don't go up on my fingers like the guy in the video. I hold my arms out to the side further, like how I figure a paddling stroke would end.
For the opposite I do hollow holds which work the front of the neck. I try to keep my neck straighter than the guy the video (kind of looking up).
Not sure how long I should hold these or for how many reps to stimulate a strength adaptation? I've read that to stimulate a strength adaptation with body weight you need to go to near failure.