Complex sentence: It was followed by the Rock Mafia remix of "See You Again", released on August 8,2008 in countries which the original version was not, expanding the success of the song by appearing on charts in several countries.
Split into simpler sentences: It was followed by the Rock Mafia remix of "See You Again", which was released in countries in which the original version was not. The remix expanded on the success of "See You Again" by appearing on charts in several countries.