Flashcam

the referenced "setMode" is this one:
http://xrl.us/bevwa9 (Link to livedocs.adobe.com)

Steps:

1.
You start flashcam with a higher resolution:
-s 1600x1200

2. in Flash/Actionscript:

cam=Camera.getCamera();
wcam = new Video(videoWidth, videoHeight);
cam.setQuality( 0, 0 );
cam.setMode(1600, 1200, 25, false);
wcam.attachCamera(cam);


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[ not sure about what you mean with "flash app [...] resize":
the flash app as a whole does not, of course, resize,
its only the resolution of the camera you can set this way ]