I finished AD 4 and 5, so I've been reverse-binging Robot Chicken. I've religiously memorized season 1-4, but have barely seen 5-8 (corresponded with my move to Boston and becoming an Adult™.) I got back to s4 so I've been doing some research and found Sweet J Presents, AKA "Robot Chicken Season Zero." It was an online show for Sony in like 2002 (which explains Sony Pictures producing RC for seasons 1-5.)
VIDEO It's actually pretty cool how, like, even the latest episodes are pretty consistent with this style. Sure there's only so much you can do with stop motion toys, but the sense of humor, timing, and even animation quality is pretty damn good for a short-lived web show.
Amazingly, even with 12 of these episodes as reference material, basically every network and comedy sketch show under the sun rejected Robot Chicken until Seth McFarlane referred them to AS. And the rest is history.
I also had no idea Seth and Sarah Michelle Gellar have been friends since childhood, I thought she was just on the show a lot because they remained friends since Buffy (similar to Seth and Mila Kunis.) Speaking of,
SMG and Kunis are credited in almost every single episode under bizarre titles (in addition to getting credited when they voice a character.)