I also kinda got that impression, what he probably meant was the D50's focusing algorithm was slow to tell the lens that it's in focus, so it should stop seeking. While the D200's algorithm was better.
I think it's the heavy pieces ofglasses in the big 80-400VR that make focussing with relatively small motor had to gerared up so slow. The travelling distance for those glass is also longer than standard lenses. Actually I can hear it grind while moving those glasses. I do not have problem with Nikkor Micro 60mm which is also not an AF-S lens.