Once again, I’m trying my best not to entirely bite into this, and definitely think this could have been a slip on words. But I just wanted to mention something.
I’ve seen people use the interviews of people saying Snake and Rayman would be in SSB4 as prove that this stuff has happened before. While it is definitely similar, one key difference is that those were interviews, where your on the spot and it’s much easier to have a slip of the tongue. This is clearly a fully scripted and edited video, where a slip like this is much more unlikely, but still possible.
Not entirely sure on the Mega Man in Brawl stuff, so maybe that might be more accurate to what’s happening right now, or maybe it was an interview as well. Don’t know the exact source for that claim.