I've talked to some people and I'm basically 100%-adjacent sure it's legitimate footage, and also that it's legitimately canned.
I was told a little bit about the senior staff beyond Bill Kopp today when I went digging -- I don't want to name anyone, especially now that the leaker has run away, because I don't know who is allowed to say what -- but that said, there was a good amount of pedigree behind this show. Some crossover with a big 2010s CN show, a streaming service's adaptation of a very difficult video game, another recent CN property that began life as a web show, and of course Bill himself is a great talent.
For further evidence here, one of the people I knew for a fact was working on the show (because Bill mentioned their partnership on a podcast where he teased the show) posted on a personal account a couple hours after this thread went live, saying they were "unexpectedly looking for work".
Other than that I don't have anything concrete past speculation. I'll update if I hear more.
My take on the whole thing is that this really blows. I was looking maybe most forward to this out of all the stuff that was going to happen for Crash soon. I was hoping this was gonna drop as part of a big 25th anniversary celebration. RIP