Complex sentence: The first was a mainstream release of "Live Monsters", an EP of live concert recordings of songs, originally recorded for "Good Monsters" and that had been previously released through the iTunes Store and the official Jars of Clay online store.
Split into simpler sentences: The first was a mainstream release of "Live Monsters", which is an EP of live concert recordings of songs that were originally recorded for "Good Monsters". The EP had been previously released through the iTunes Store and through the official Jars of Clay online store.