Casper Kelly: My direction to him was very specific for each shot, but in my head he is a man who tried to be a sitcom dad with his attempt at a Cosby sweater and such but just will never allowed to be a part of this world he has to dwell in. So hes gotten a little bitter and vengeful about being left out.
Another growing theory is that he's just one of many of the Always Chaotic Evil forces of B.R.o.t.H.
"Intronitis" being a disease that professional doctors are horrified by calls into question if it's a good thing that Smarf reset the show.
It also creates a possibly that The Killer is ultimately doing a good thing by attempting to destroy the show.
Also, the fact His credits glitch out suggests The killer is at worst a carrier of the infection, but possibly even could be immune to Intronitis.
The show is actually about a group of people who are all rampant sufferers of Intronitis who were put onto the show purely to give them something to do with their lives. If you look at some of the younger cast members, they are slumped, seemingly bored out of their minds. Imagine if you were stuck in a sitcom purely since a name floats into view a short distance in front of you. No wonder the doctor wants to commit suicide!
Applicability: Dozens of theories have been made about the short's applicability to real television, such as it being a critique of cookie-cutter entertainment, forced retools, multiple writers/showrunners working on and overcomplicating long-running sitcoms, the dark undertones behind cheery family-friendly shows, or even an attempt to overthrow television as a whole. Word of God is that there's probably a message in the short somewhere, but the main reason why they made it was just to screw with people's minds at four in the morning.
Award Snub: The short was wildly popular on the Internet and received high praise for its twisting of TV cliches, but didn't even get nominated for the 2015 Primetime Emmy for Outstanding Short-Format Live-Action Entertainment Program
Awesome Music: Some of the variations on the main theme get absolutely amazing, like the crime drama variation and the G.I. Joe parody one.
Gwydion Lashlee-Walton, for his awesomely complicated name. And it's the actor's real one, to boot!
Everyone Is Jesus in Purgatory: And how. The amount of slightly ponderous chin-scratching clickbaity articles about what this short is really about (and the various abstract theories they're coming up with) is getting more insane than the short itself.
Around 30 seconds into the short there is a brief shot of Savannah getting her face painted with a paint roller. As pointed out on the Reddit AMA, a month earlier there had been a query on Facebook, Reddit, and Metafilter about finding a show opening with such a shot, which was so hard to find that even librarians from the Library of Congress were stumped.
A work parodying sitcom tropes that gradually becomes sinister and surreal? Add in superheroes and you've got WandaVision.
Mondegreen: The lyric "a scoop of kids" sounds a LOT like "stupid kids" to the average listener's ears the first time they watch this short.
The Scrappy: Smarf appears to be an invoking of this trope, with his ugly design and puppet contrast to the live-action actors. Rescued from the Scrappy Heap when he uses his Eye Beams to explode the Killer. Also when he presses the reset button in his (would be) last moments. He is, in fact, the closest thing this short has to a hero.
Tastes Like Diabetes: Much of the opening's super-saccharine nature, especially the shots of the little kids and Smarf shooting rainbows out of his hands. Then the Killer comes to change all that.
Fair for Its Day: The novel in general is a critique of race relations in 1930s America nevertheless written in 1930s America, and it's safe to say that by modern standards it shows. Nevertheless, it is still arguing for greater tolerance, openness, equality and racial justice. In particular, while Archie Goodwin's conduct is quite racist (if still not as bad as some of the other characters) and the novel doesn't spare him from criticism, a case can be made that by contemporary standards he's nevertheless still fairly tolerant. He freely uses several racist slurs and displays some rather prejudicial ideas about individuals of other races, but seems to hold no particular animosity or hostility towards those individuals. At a couple of points he also helps several African American servant characters with various menial tasks without resentment or complaint, something that would have been otherwise almost unthinkable in 1930s West Virginia.