The phrase "extended cameo" means when a well-known person briefly appears in a movie or show for a slightly longer amount of time than a regular cameo appearance. Full definition
Morgan Fairchild's theatrical film work has been by and large unremarkable, save for an amusing extended cameo in 1985's Pee - Wee's Big Adventure. (rottentomatoes.com)
Mark Wahlberg also has a fairly amusing extended cameo as a former client of Claire's, to whom the couple comes for help. (joblo.com)
Also, ook out for extended cameos from History Boys cast members Dominic Cooper and James Corden, who turn up as an actor and market trader restectively. (thehollywoodnews.com)