Without getting into all the physics and engineering crap (that I'm sure I don't FULLY understand), he's got what looks to be ~7-8" of separation at the axle, but maybe 3" at the frame. This causes anti-squat numbers to go up.. more separation at the frame will lower the number. The more the links look like a triangle from a side view, the more AS you'll have typically. (A very broad generalization)
Honestly, the best thing that I did was download the 4-link calc and play with the numbers, and see how it changes things.. There are some good books that can explain what alot of the terminology means, usually accompanied by a big equation, which the calc does for you.
[disclaimer]
I'm not trying to sound like I know all there is to know about linked suspension, far from it.. But I have learned a ton from researching my own future setup, and have re-designed it several times as I learn more..
As much of an asshole as I am, I really do like to offer help to people when I can..[/disclaimer]
