Just a word of caution for anyone that would want to use thos in an actual survival situation. If you're really lost, the best thing to do is stay put and wait for someone to find you. If you have to move, knowing which direction is North is pretty useless unless you know enough about where you are and the surounding area. And even then, in such situations, topographical landmarks will likely be more useful.

Not to be a nay sayer, it can be fun to do, and perhaps even useful in some situations. But probably not something that's going to save your life, no matter how many time Bear Grillis used it.