That's true, although most of the technical knowledge required for these matches is related to the player histories, map features/stats, and opening build orders. Those could all be learned and memorized within a very short time if one were really committed to doing so. The rest of it is speculation, play by play restatement of the obvious, and what they call "color" (humor, analogies, etc.).

I used to be very weak on opening build orders, but I've learned a lot from watching other commentators. You just have to watch for anything unusual and recognize it when it occurs. Technical knowledge would still be my weakest area, since I was never that great of a player, which is why I'm reluctant to commentate on Starcraft 1 right now. Sure, I could BS the aspects I didn't know, which many/most of the commentators do, and most viewers wouldn't know the difference, but I'd feel like a bit of a fraud and besides, it's much easier to commentate when you really know what you're talking about. This week on Commentator Idol they had a (purportedly) really good player named Chill as a guest judge, and he tore into many of the contestants for making technical errors. At the time, what the commentators said seemed vaguely plausible, but after I heard Chill's criticisms, I knew that he was definitely correct and the commentators were wrong. I wouldn't want that to be me, however well I could make up for it in other areas. I'm excited about commentating Starcraft 2, again, because everybody will be on fresh ground and I'll be able to learn the intricacies of it, the maps, and the players along with everybody else. Maybe you could do it too, or we could do some dual commentaries.

I'm sure you have enough technical knowledge, provided you looked up map and player statistics before each match. They're listed somewhere, but I never bothered to actually find them. I don't foresee any problems you would have announcing. The biggest problem people have is getting nervous and feeling like they have to have some brilliant insight every second, causing them to panic and stutter, but neither of us would suffer from that.

My favorite commentators right now are Rise and Cholera. They're laid back, intelligent, have unique casting voices, and funny. Klazart used to be the best of them all, but he hasn't had one out for a while. Interestingly, a lot of commentators who started out very poorly became some of the best with practice, including Cholera. I've never seen a commentator who didn't vastly improve with practice, and surprisingly, the youtube users are overall very supportive and positive (probably due to the self-selecting nature of starcraft). I'd like to do it, besides for the fun of it, just to improve my public speaking as they have done.