Go to a mountain where you can hit the slopes and film someone snowboarding. Ensure that the mountain you visit has snowboarding slopes (preferably with ramps to jump off of and rails to grind on) and that the snow is not melted to the point where one cannot snowboard on it (it is best to go during the winter months).
Enter the mountain's ski/snowboarding slopes and ride the ski lift up to the top of your desired slope. To make the film more exciting, request that the snowboarder do many stunts and tricks, such as jumps off of ramps, and grinds off of rails. If the snowboarder agrees, ensure that you ride a ski lift that transports you to the top of a slope that contains many ramps and rails.
Leave the snowboarder at the top of the slope. Ride partially down the slope until you find a location from which you would like to film (to catch action shots, ensure ramps and rails are within filming range). Station yourself on the outermost edge of a slope so as to avoid collision with any riders.
Set up your camcorder so it is pointing to the location from which your friend will be riding into visible range. Use a tripod for added stability and to decrease the amount of motion blur. If possible, set up multiple cameras on tripods to capture the action from multiple angles. If you have multiple cameramen, it will be easier to record multiple angles. If the multiple camera option is not viable, film several rides from several different angles to create a similar effect. Otherwise, your film may seem bland and lack variety.
Give the snowboarder a signal to notify him that he can commence his ride down the slopes.
Turn on your camcorder, put it in record mode, and aim it at your friend while she is descending from the top of a slope. Track the snowboarder's movements down the slope with your camcorder. Zoom in and out when appropriate to accommodate for distance and to record details of the snowboarder's ride.
Shoot a more dynamic camera angle by filming the snowboarder while riding side by side or behind him (or have another cameraman do it for you). You can further enhance your video by filming from an aerial view if you have access to a helicopter or can film from the ski lift.