The beauty of these exercises are that you can make it as hard or as easy as you like.
My favourite version - forwards 10-20m, sideways to the right 5-10m, backwards 10-20ms, sideways to the left 5-10m. I like it with the hips low like in the picture and the opposite arm and leg moving at the same time. You can go slow or fast, on your toes or on your knees (that can hurt so on a padded floor or grass is better)
Other variations include legs straight, same arm-leg moving together, and hips high. You can also vary the movement path of your feet and hands - to the outside and wide or inside and narrow. Another awful variation (as in really hard for someone my size) is to get down close to the ground like a Spiderman crawl...but then it wouldn't be a bear crawl would it?
I am not sure if there are any other exercises that do so much in a warm-up - it loads and moves your joints, it warms the body up and primes the neuromuscular system, it can be used to increase mobility and flexibility, etc etc. A reckon a Thruster would be my next favourite and I don't think it is in the same league as bear-crawls.
What is your favourite ONE exercise that targets as many joints as possible - let's talk!