You can get more details on this by checking the other posts here on "Sat C" but the basic idea is that the special Sat C LNB transforms the frequencies of the transponders on the 110 satellite down to slots that aren't used on 119. That way, when the two LNBs are combined on one lead and your STB sees a bunch of new 119 transpoder signals (which are actually coming from the 110 bird) in slots that used to be blank.