You need a knife throwing "range". Find a place like a garage where you can setup a broad backstop (I like plywood covered with old carpet or flattened cardboard boxes). Lay down some more padding under your target area to keep your point off the floor. Hang targets that won't bounce back your knife. I like about 10 layers of cardboard stuck together with tape or spray adhesive.
Find a way of holding your knife that lets you throw strongly and consistently. Find a way to step towards the target and throw the knife consistantly. DO NOT COMBINE LOTS OF LITTLE ADJUSTMENTS, first work on one range, one grip, one swing, one step...that you can do consistently. Practise at this one close-in single-turn or half-turn distance (depending on whether you throw from the blade or handle). You should get to the point where you can nail something about the size of a playing card at short range.
The next step is to move back to a distance where the knife makes one additional turn and sticks in the target using the exact same throwing technique. Mark off the floor with chalk or something to identify your one-turn and two-turn distances. Practise till you can consistantly stick the blade accurately from those two distances.
Third level is to find some MINIMUM adjustment to your throw that lets you stick the knife between those two fixed ranges. For me, I stretch my stride to lengthen my throw outside of my normal "marks" and step short and give a little more whip to my wrist when I am inside my marks. I would expect you to be able to nail a 2x4 pretty consistantly on your knife range when you have your distances labeled and your consistant technique refined.
Have fun.
As for the movie stuff, It is hard to judge distances in a variety of locals accurately enough to stick a knife beyond 2 or 3 turns. For me this is around 18 feet. If you have a couple knives you can check your range with the first throw and improve your chance of sticking with the second throw. I would try and get closer, but stay outside of arms reach.
[This message has been edited by Jeff Clark (edited 06-05-2000).]