Similar to one-footers speed is not the most important issue. Just head towards the jump at your normal jumping speed.
Near the highest point of the jump pull both feet off of the pedals and kick them straight out to the sides. The farther
up and out from the bike you can get these the cooler they look.
The key to this trick is having your pedals not move on you. Before you start taking both feet off make sure that your
pedals aren't going to disappear on you when trying to land.
As with one-footers just leave your feet out as long as you are comfortable with. But, unlike one-footers it is very important
to get your feet back on the pedals before you land. Once your feet are back on the pedals, land as you normally would.