You can access the 'Full Desktop Button' through the 'Toolbar'.

Programs such as MSN messenger, Skype, PalTalk, ICQ, and others use the video resolution of 320x240 pixels to broadcast live video from your webcam. ScreenCamera also has that same video resolution in order to be compatible with these programs. So, when you click the 'Full Desktop Button' ScreenCamera actually shrinks your full desktop screen to fit the video resolution of 320x240 suas as on the example bellow: