Easter Egg: Firebugs (PS1)
Channel: ImminentTortoise
Date: 2013-03-04

Here's how I got to the point in the video, for those that want to know:
I completed all of the Phoenix League
After completing all of that I unlocked the Bonus Area in Practice Mode
I unlocked two modes, the first one being Charlie's Mode
I entered that, on the second lap I think I boosted, went up the side of the left wall of the first curve of the track and flew into the top of the small cave-type thing, suddenly the graphics went odd and I ended up the in room you see in the video.