Complex sentence: It was at this time, 1999, that LaMarche began work on "Futurama", and since "Futurama" LaMarche has continued to work steadily in television, including guest roles on "The Simpsons" (where he once again parodied Orson Welles).
Split into simpler sentences: It was at this time, 1999, that LaMarche began work on "Futurama". Since "Futurama" LaMarche has continued to work steadily in television, including guest roles on "The Simpsons" (where he once again parodied Orson Welles).