Well, actually, I post on a very nice Kevin and HtLJ board and some of the people there already have their season 6 box set so they share with us its content :)

The 5th disc seems to be the CD-Rom.

But we don't know yet what will be in the best buy extra set !!!

Here is the link to the HtLJ board :

http://www.sf-fandom.com/vbulletin/forumdisplay.php?s=&daysprune=60&f=20

Cheers

D-Chan