Complex sentence: Lav Diaz is the leading figure in experimental Tagalog films whose works include excruciatingly long epics about Filipino life some of which run up to 10 hours often testing the endurance of viewers.
Split into simpler sentences: Lav Diaz is the leading figure in experimental Tagalog films. His works--including excruciatingly long epics about Filipino life (some of which run up to 10 hours)--often test the endurance of viewers.