I just saw that movie for the first time not too long ago, and now I know what the soap thing was all about.
That movie is intense. It was frequently being shown on TBS or one of those cable channels recently. In it, two dudes make money by selling "high end" soap that they create using fat obtained through dumpster diving and stealing medical waste, that is--LIPOSUCTION discards--human fat!
That's not the point of the whole movie or anything, it's just of major interest to soapmakers. But now you know why that bar of soap on the cover of the video is there.