Simplify the following text for a Grade 11 native English-speaking person.
Original: Between January 23 , 2007 and September 11 , 2007 , Nickelodeon released five DVD sets for the season : four sets containing five episodes each , and a fifth DVD collection of all twenty episodes .
Simplified: Between 23 January 2007 and 11 September 2007 , Nickelodeon released five DVD sets for the season : four sets had five episodes each , and a fifth DVD collection of all twenty episodes .