This is my favorite way to film, but it's not easy holding a pole while riding! The key is to hold it at such an angle that the pole won't be noticeable, and that you hold it high enough so the board is included from top to bottom.
P.S. This pole is for a smart phone (it will hold any Android or iPhone, and both will work with the Bluetooth built-in remote on the handle of the pole). You can also mount a GoPro, but you will need a rollbar mount. Just be warned that's significantly heavier to hold. Make sure you practice at a safe environment since it might affect your balance if your arm is immobile from having to hold the device. Furthermore, if you want this pole, let me know, and I can help you look. I got mine when I traveled in Asia, but I'm sure we can find you something online! ;)
Oh, BTW, I wear safety gear. My gear was in the mail the week when I filmed this. :P Please be safe!