I made an account just now to try to help you guys.
I HAD the same problem with my webcam and I think I know the solution.
While in AIM, go to "Edit" >> "Settings" (Or press F7) then go to the "Enhanced IM" tab. Look under "Audio and Video" and select the webcam of your choice for "Microphone" and "Camera".
This is how I solved my problem. Hope this helps you!