Complex sentence: New material started to appear in 2011 for their third album, the first single from which is entitled "Left Is Best" The sneak-peek promo video for "Left Is Best" first appeared on YouTube in December 2011.
Split into simpler sentences: New material started to appear in 2011 for their forthcoming third album, the first single from which is entitled "Left Is Best". The promo video for "Left Is Best" appeared on YouTube in December 2011.