I just upgraded to those exact Lead screws on my 10" i3v. I used 400 steps. Works perfectly. So glad I did this upgrade (my threaded rods were pretty bent after a recent move.)

What mounting method did you use? Just out of curiosity. I used http://www.thingiverse.com/thing:842213 which has been working great for about 2 weeks.

After watching the video you linked, you might want to to look at your acceleration as well as your max feedrate. My DEFAULT_MAX_FEEDRATE for Z is 50 (the stock was 5, too slow for me) and my DEFAULT_MAX_ACCELERATION is 100. Hope that helps, I'll try to answer any questions you have.