A briefing should be as brief as possible, hitting on big picture things. If it gets too detailed, then you won't be able to remember all the stuff that was mentioned... then, the briefing was counter-productive. Some airlines require that long dissertations be read. This is a bad idea, as I wouldn't remember anything after the long speeches required at some carriers. The briefer the better.
NV pilot --
While one pilot is reading the briefing, the other pilot should be... FLYING THE PLANE!!! NOT looking at the FMC!