Never disclaim yourself unless you have a good out. For example “Hey, I don’t know too much about this… but I know Brett in the audience can totally tell you anything you need to know, so Brett, stand up and tell us exactly how to cook the kittens to make them extra delicious!” is fine, but “uhhm… sorry, I’m not entirely sure what this whole part of the softare is about, but I’m sure it’s really useful if you, uh, have a use for it.” is not.

Also, if Brett won’t stand up and talk, he’s the loser for not doing so, and you’re not a loser for not knowing anything about extra spicey kittens.