first, make sure your weight is centered over the balls of your feet and that you have a nice base. that is the most important thing. too much pressure from leaning back will make your tails wash out.
the only way you will get to be good at skiing switch is to practice. next time you are on the mountain, try and ski switch exactly how that video says. if you are doing what i used to, you will start off great, but right at the apex of the turn, you cant switch turn direction. if that is the case, here is what to do:
get on a nice, easily sloped run, and start skiing switch. dont pop switch yet, just start off backwards. begin your turn like that video says, and just do what you always have. when you get to the point in your turn that makes you spin all the way around, memorize that feeling. really try and get a feel for whats happening. next time, right before that happens, start to transfer your weight from ski to ski, making sure you bring them even to each other when you face (backwards) the fall line. do this enough, and try to get a good handle on how it feels. keep practicing that, and you should be skiing switch no problem. good luck!