Top speeds? Huh?

I've seen "World R/C speed record" at 79mph somewhere in the web, but I've also seen people hitting 80-90mph with random vehicles on youtube as well. (Even higher with TC and such.) So, what's up with that? Why does one site claim that 79mph is the world speed record, while there are much higher speeds recorded elsewhere? I don't understand. Is it relative to a specific setup, perhaps? And vehicle? If so, why isn't that stated along with the record?

And also, I was wondering about something, if I put a Neu 1515/1y (2200kv) in a Rustler/Stampede/Hyper 10tt, for example, and geared it max, and ran it at 6s, wouldn't that easily hit 70mph ?