The Beware Background thing only comes with the step charts and the videos. Go to
www.ddruk.com and download the DDR 1st Mix-Extreme packs or as many packs as you like. Take the .sm file from the Beware Background thing and put the .sm file into the file of it's respective folder of the DDRUK pack. So for 1998 take the .sm file from Beware and put into 1998's folder in the DDRUK DDR Extreme pack.
Finally put all of the videos into Stepmania's random video's folder. Reload your song list for good luck.