The host of the late-night talk show "Jimmy Kimmel Live" has been dating Silverman, also a comedian, for several years.
Pitt plays a delivery guy who brings Kimmel and Affleck a cake congratulating them on their newfound love, while Cheadle appears with Cameron Diaz, Robin Williams, Macy Gray, Lance Bass, Meat Loaf, Huey Lewis and others in a scene that spoofs the likes of such star ensemble songs as "We Are the World."
Harrison Ford even makes an appearance in another part of the video, blowing a kiss at Kimmel and Affleck from his car.
Kimmel said on his show that Silverman's video has been seen by more than 8 million people on ABC.com and YouTube
MTV.com said Kimmel's reply has gotten more than 2.5 million hits on YouTube since it debuted on his show this week.