i'm no pro but it definitely looks like two things to me: mainly, committment - you weren't quite perpendicular to the rail i don't think; secondly, try to concentrate on leaning forward so your skis are flat. so basically, exactly what NMassault said.
well I never ground a down flat but im guessing it would be kinda like a down flat down. I think that NMassault* had it exactly but another thing that also seems like your having trouble with is that your kinda standing strait up. so I would say just crouch down a little and it also looks better if you get it.
