Not sure which part, but by the first part, I mean that OldSub4 and his training partners noticed DRAMATIC increases in performance when they added workouts specifically targeted to improve their aerobic strength- the cutdowns he mentioned, the tempo work, the other "threshold" stuff.
As for the second part, I meant that in order for an elite 800 runner to reach his potential, he needs to be able to produce tons and tons of lactate, especially in the last 200 of a race, in order to minimize deceleration. He also needs to be able to handle the tons of lactate he's already produced in the first 600 because the 800 isn't long enough for tons of buffering to take place.
Several guys with 52 second 400s and 2:00 800s have posted in this thread= their problem is not in their ability to produce lactate, it's that they're producing tons of lactate at 60/400 pace. If a coach gives workouts to target that threshold (which may not be traditional "lactate threshold" workouts like 20min at 60min race pace or whatever) then the athlete produces way less lactate at 60/400- now, at say, 15mmol (I'm pulling that number out of my ass, it's just an example) instead of traveling at 60/400, the athlete is traveling at 56/400 and runs 1:52.
My HS coach always drilled into my head that an 800 is all about who can get to 600m the freshest, not about leg speed.