I think the idea is you download the media kit one, buy the game online, and download the cover and cd images.
Then find yourself a printable CD, a blank dvd case, and you have a full game for yourself to keep.
Some people like games on their shelf, plus if the site was to ever go down you'd have a hard copy of it.
Your allowed it installed on 4 machines, but your only supposed to use it yourself Its not a 3 people can get out of paying their £5-10.