Navigation is one thing, but knowing how to feed yourself in the wild is more important (after all, if you’re dead it’s not like you’ll need to know which way the closest road to civilization is.) Many is the lost hiker or camper who met their end because they ate something they shouldn’t have. Know what to do, and you will be able to fill your stomach with stuff that won’t leave you sick or dead.
The edibility test shown in the video is the same one you may have read about in a book about survival or camping. Obviously you should wait longer between steps, as a bad reaction may take time to occur; if you don’t wait, you may be compounding the problem by eating something which isn’t safe. You’ll notice the test was done with a raw specimen – an important detail, since you may not always have enough fuel for a cooking fire, or the time to build one. Also, cooking may inactivate chemicals which would otherwise prove deadly, and you wouldn’t know this until it was too late.
For those wondering, yes, certain types of bark are edible. You’ll need to find out which trees in your part of the world can be used for eating, though.