I have a document camera I want to use to record a podcast...Installed the mac software cannot get it to record on the MacBook

click the camera icon in imovie. this will start an import window. there's a dropdown menu that lists cameras found.

the drop down only lists the one camera even though I can use the other camera with its own program.

Hmm.. USB cam? Make sure ichat hasn't popped up and grabbed it, or your camera app isn't running. Only one app at a time can have cam.

yes it is a USB (avervision) I'll check..is there anywhere I can see the devices connected to the machine??

No, just check for other running apps. Also check preferences on imovie for video setup. Under the iMovie menu