‘The Muppets’: The rules of writing for a pig and a frog [video]

Turns out writing a Muppet script is no easy task. Star Jason Segel and his “The Muppets” screenwriting partner Nicholas Stoller, who previously collaborated on “Forgetting Sarah Marshall” and “Get Him to the Greek,” spent four years writing a script that both honored the Jim Henson Muppet movies of the past and remained relevant today, they told an audience at the Envelope Screening Series.

That required learning the specific rules of each Muppet and simplifying a very complicated initial premise. Learn more about a rather complex writing process -- one that may have involved adult-size Muppet costumes -- ¿in the video clip below.