You could just Ctrl+Click on the swf when it's playing in your browser
and swap it in your Flash settings...
Or the proper way of doing it would be along the lines of getting the
mac camera:
private function setupCamera():void
{
vid = new Video(640, 480);
var camIndex:int = 0;
for (var i : int = 0 ; i < Camera.names.length ; i++ ) {
if (Camera.names[ i ] == "USB Video Class Video" ) {
camIndex = i;
break;
}
}
cam = Camera.getCamera(String(camIndex));
cam.setMode(320, 240, 30);
vid.attachCamera(cam);
addChild(vid);