This animated short, included on the tenth anniversary "Clerks X" DVD set, is a deleted scene (so to speak) that was excluded from the original shooting script of the film; in other words, it was written but never actually filmed.
Using the "Clerks" TV show animators, Kevin Smith got the original crew back to voice their characters and re-film the deleted scene -- as a cartoon.
There's a nice tie-in to "Chasing Amy" here. If you've seen that movie, Alyssa (Joey Lauren Adams) references her best friend who dies; in this scene, we view the funeral. There's some funny stuff with Randal that happens and the animation just works well as a tie-in to both series.
This has gotten some bad reviews here on IMDb but I liked it for what it was. It's pretty funny and fits into the chronological timeline of "Clerks." It's an entertaining short scene and if you ever get the DVD, make sure to watch it after the film as I'm sure you'll enjoy it for what it is.