Modeling the gopro guy was pretty easy. Just model a go pro and a stickman. The rig was fairly simple as the head did not have to have any animation. Getting him to ride the bike was a little harder. I also have a skier version and a snowboarder.
Once you know how to rig a basic biped character (stands on 2 legs) its easy to adapt to your own characters. The animation is just a case of watching reference videos (youtube is good for this) and adapting the movements for your own animation.
What I find the most fun, is working on a scene from start to finish, like the last shot, or the shot from the La Nina episode. Both those I did everything on and I had total control over the look from start to finish. Admittedly there also the most work.