If Brock Lesnar defeats Frank Mir, he could end up becoming the biggest story of 2008 for The UFC. I know it ain't scientific, but when I tell one of my friends that used to be into wrestling that Brock is fighting, they are instantly interested. This is why they're using the pro wrestling footage: If Lesnar is a complete flop, they might as well get one good PPV number from him.
I think Lesnar is going to win this, but I'm as much in the dark as anyone else. I've read stuff coming from his camp, and have talked to some people that have trained with him in Minnesota, and it's all very positive. However, most stuff coming from camps is propaganda, so you never know. Frankly, the fight will probably come down to who gasses first: The virtual rookie or the often out of shape veteran.
At this point, Frank Mir is just a generic "former champion." His name means nothing to the post-TUF generation, but the champion monicker does. The hype for Mir the UFC is doing is really quite a spectacle. They are almost pretending like his last fight was the one where he broke Tim Sylvia's arm.
If Lesnar wins, the hype will be outrageous, and it will be worth remembering that this is not the old Frank Mir he beat. If Mir wins, people will start acting like he's a huge contender, when all he did was beat a guy in his second MMA fight.
Ultimately, the fight really means nothing, and won't determine much. It's just a spectacle, and there's nothing wrong with that. MMA spectacles are my favorite thing about Japanese MMA, and I wish the UFC would do it more.