The Fitness value tells the user how fast of a download he can expect.
Ed2k is notoriously slow, its the slowest there for red and 1 bar
Hosters without having a premium account are also not very fast therefor 2 yellow bars
Torrent is quite fast, its usually have really decent speeds therefor 3 green baars,
And so are hosters if you have a premium account for one of them set, also 3 green baars,
And if there is a neo hash known than you can obviusly download the file using any means therefor 4 green bars.
Live free or die trying!