Complex sentence: He has been a researcher for the program for 33 episodes from 2004 to 2005 and served as an associate producer from 2005 until 2012 for 143 episodes.
Split into simpler sentences: He has been a researcher for the program for 33 episodes from 2004 to 2005. And served as an associate producer from 2005 until 2012 for 143 episodes.