Such a cool video. They ride my favorite trail so fast it's crazy. I also know where all those other jumps like the gap between the two spines and the one that eric porter overshot are.
joshua: I strongly recommend against it. Pro teams like DB5 are running prototype gear and non-production frames. Don't copy what you see. It's not what it appears, and you are not a pro.
putting a longer fork on the bike will raise the front end putting the wheel further foward, thus slackening the head angle the fork will be pointing more across than is was doing before, which is no bad thing. I would contact diamondback before you do it and check it will not void you warranty.
I forgot to add you probably shouldn't go over 180mm. measure the axle to crown length and compare before you make a decision. Keep in mind 20mm is less than one inch